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Red Hat Developer Toolset 2.x User Guide Installing and Using Red Hat Developer Toolset Jaromír Hradílek Jacquelynn East Matt Newsome Red Hat Developer Toolset 2.x User Guide Installing and Using Red Hat Developer Toolset Jaro mír Hradílek Red Hat Engineering Co ntent Services [email protected] m Jacquelynn East Red Hat Engineering Co ntent Services [email protected] m Matt Newso me Red Hat So ftware Engineering mnewso [email protected] m Legal Notice Copyright © 2013, 2014 Red Hat, Inc. T his document is licensed by Red Hat under the Creative Commons Attribution-ShareAlike 3.0 Unported License. If you distribute this document, or a modified version of it, you must provide attribution to Red Hat, Inc. and provide a link to the original. If the document is modified, all Red Hat trademarks must be removed. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. Red Hat, Red Hat Enterprise Linux, the Shadowman logo, JBoss, MetaMatrix, Fedora, the Infinity Logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries. Linux ® is the registered trademark of Linus T orvalds in the United States and other countries. Java ® is a registered trademark of Oracle and/or its affiliates. XFS ® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries. MySQL ® is a registered trademark of MySQL AB in the United States, the European Union and other countries. Node.js ® is an official trademark of Joyent. Red Hat Software Collections is not formally related to or endorsed by the official Joyent Node.js open source or commercial project. T he OpenStack ® Word Mark and OpenStack Logo are either registered trademarks/service marks or trademarks/service marks of the OpenStack Foundation, in the United States and other countries and are used with the OpenStack Foundation's permission. We are not affiliated with, endorsed or sponsored by the OpenStack Foundation, or the OpenStack community. All other trademarks are the property of their respective owners. Abstract Red Hat Developer T oolset is a Red Hat offering for developers on the Red Hat Enterprise Linux platform. T he Red Hat Developer T oolset User Guide provides an overview of this product, explains how to invoke and use the Red Hat Developer T oolset versions of the tools, and links to resources with more in-depth information. Table of Contents Table of Contents .Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 ............ 1. Document Conventions 10 1.1. T ypographic Conventions 10 1.2. Pull-quote Conventions 11 1.3. Notes and Warnings 12 2. Getting Help and Giving Feedback 12 2.1. Do You Need Help? 12 2.2. We Need Feedback! 13 . . . . . I. Part . . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 ............ .Chapter . . . . . . . . 1. . . .Red . . . . Hat . . . . .Developer . . . . . . . . . . .T. oolset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 ............ 1.1. About Red Hat Developer T oolset 15 1.2. Main Features 17 1.3. Compatibility 18 1.4. Getting Access to Red Hat Developer T oolset 19 1.4.1. Using RHN Classic 19 1.4.2. Using Red Hat Subscription Management 20 1.5. Installing Red Hat Developer T oolset 21 1.5.1. Installing All Available Components 22 1.5.2. Installing Individual Package Groups 22 1.5.3. Installing Optional Packages 22 1.5.4. Installing Debugging Information 23 1.6. Updating Red Hat Developer T oolset 23 1.6.1. Updating to a Minor Version 23 1.6.2. Updating to a Major Version 24 1.7. Uninstalling Red Hat Developer T oolset 24 1.8. Additional Resources 24 Online Documentation 24 See Also 25 . . . . . II. Part . . .Integrated . . . . . . . . . . . Development . . . . . . . . . . . . . . Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 ............ .Chapter . . . . . . . . 2. . . .Eclipse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 ............ 2.1. Installing Eclipse 28 2.1.1. Building Eclipse from the Source RPM Packages 29 2.2. Using Eclipse 29 2.2.1. Using the Red Hat Developer T oolset T oolchain 29 2.2.2. Using the Red Hat Enterprise Linux T oolchain 30 2.3. Additional Resources 31 Installed Documentation 31 Online Documentation 31 See Also 31 . . . . . III. Part . . . Development ..............T . .ools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 ........... .Chapter . . . . . . . . 3. . . .GNU . . . . .Compiler . . . . . . . . . .Collection . . . . . . . . . . .(GCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 ........... 3.1. GNU C Compiler 33 3.1.1. Installing the C Compiler 33 3.1.2. Using the C Compiler 33 3.1.3. Running a C Program 35 3.2. GNU C++ Compiler 35 3.2.1. Installing the C++ Compiler 35 1 Red Hat D eveloper Toolset 2.x User Guide 3.2.2. Using the C++ Compiler 3.2.3. Running a C++ Program 3.3. GNU Fortran Compiler 3.3.1. Installing the Fortran Compiler 3.3.2. Using the Fortran Compiler 3.3.3. Running a Fortran Program 3.4. Additional Resources Installed Documentation Online Documentation See Also 35 37 37 37 37 39 39 39 40 40 .Chapter ........4 . ...binutils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. .1. . . . . . . . . . 4.1. Installing binutils 41 4.2. Using the GNU Assembler 42 4.3. Using the GNU Linker 42 4.4. Using Other Binary T ools 43 4.5. Additional Resources 43 Installed Documentation 44 Online Documentation 44 See Also 44 .Chapter . . . . . . . . 5. . . .elfutils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. .5. . . . . . . . . . 5.1. Installing elfutils 45 5.2. Using elfutils 45 5.3. Additional Resources 46 See Also 46 .Chapter . . . . . . . . 6. . . .dwz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. .7. . . . . . . . . . 6.1. Installing dwz 47 6.2. Using dwz 47 6.3. Additional Resources 47 Installed Documentation 48 See Also 48 . . . . . IV. Part . . . Revision . . . . . . . . . .Control . . . . . . . .Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. .9. . . . . . . . . . .Chapter . . . . . . . . 7. . . .Git . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 ............ 7.1. Installing Git 50 7.2. Configuring Git 50 7.2.1. Configuring the Default T ext Editor 50 7.2.2. Setting Up User Information 50 7.3. Using Git 51 7.3.1. Creating a New Repository 51 Initializing an Empty Repository 51 Importing Data to a Repository 51 7.3.2. Cloning an Existing Repository 52 Cloning a Git Repository 52 Cloning a Subversion Repository 52 Cloning a CVS Repository 52 7.3.3. Adding, Renaming, and Deleting Files 52 Adding Files and Directories 52 Renaming Files and Directories 53 Deleting Files and Directories 53 7.3.4. Viewing Changes 53 Viewing the Current Status 53 Viewing Differences 53 7.3.5. Committing Changes 54 2 Table of Contents 7.3.6. Sharing Changes Pushing Changes to a Public Git Repository Creating Patches from Individual Commits 7.3.7. Updating a Git Repository 7.4. Additional Resources Installed Documentation Online Documentation See Also 54 54 54 55 55 55 55 55 . . . . . V. Part . . .Debugging . . . . . . . . . . . .T.ools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 ............ .Chapter . . . . . . . . 8. . . .GNU . . . . .Debugger . . . . . . . . . . .(GDB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 ............ 8.1. Installing the GNU Debugger 58 8.2. Preparing a Program for Debugging 58 Compiling Programs with Debugging Information 58 Installing Debugging Information for Existing Packages 59 8.3. Running the GNU Debugger 59 8.4. Listing Source Code 60 8.5. Setting Breakpoints 62 Setting a New Breakpoint 62 Listing Breakpoints 62 Deleting Existing Breakpoints 62 8.6. Starting Execution 63 8.7. Displaying Current Values 63 8.8. Continuing Execution 64 8.9. Additional Resources 65 Online Documentation 65 See Also 65 .Chapter . . . . . . . . 9. . . .strace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 ............ 9.1. Installing strace 67 9.2. Using strace 67 9.2.1. Redirecting Output to a File 68 9.2.2. T racing Selected System Calls 68 9.2.3. Displaying T ime Stamps 69 9.2.4. Displaying a Summary 70 9.3. Additional Resources 70 Installed Documentation 71 See Also 71 .Chapter . . . . . . . . 10. . . . . memstomp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 ............ 10.1. Installing memstomp 74 10.2. Using memstomp 74 10.3. Additional Resources 76 Installed Documentation 76 See Also 76 . . . . . VI. Part . . . Performance . . . . . . . . . . . . . . Monitoring . . . . . . . . . . . .T. ools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 ............ .Chapter . . . . . . . . 11. . . . . SystemT . . . . . . . . . ap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 ............ 11.1. Installing SystemT ap 78 11.2. Using SystemT ap 79 11.3. Additional Resources 79 Installed Documentation 79 Online Documentation 80 See Also 80 3 Red Hat D eveloper Toolset 2.x User Guide .Chapter . . . . . . . . 12. . . . . Valgrind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 ............ 12.1. Installing Valgrind 81 12.2. Using Valgrind 82 12.3. Additional Resources 82 Installed Documentation 82 Online Documentation 83 See Also 83 .Chapter . . . . . . . . 13. . . . .OProfile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 ............ 13.1. Installing OProfile 84 13.2. Using OProfile 85 13.3. Additional Resources 85 Installed Documentation 85 Online Documentation 86 See Also 86 .Chapter . . . . . . . . 14 . . . .. Dyninst . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 ............ 14.1. Installing Dyninst 87 14.2. Using Dyninst 87 14.2.1. Using Dyninst with SystemT ap 87 14.2.2. Using Dyninst as a Stand-alone Application 89 14.3. Additional Resources 94 Installed Documentation 94 Online Documentation 95 See Also 95 . . . . . VII. Part . . . .Getting . . . . . . . . Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 ............ .Chapter . . . . . . . . 15. . . . . Accessing . . . . . . . . . . . Red . . . . .Hat . . . .Product . . . . . . . . .Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 ............ Red Hat Developer T oolset 97 Red Hat Enterprise Linux 97 .Chapter . . . . . . . . 16. . . . . Contacting . . . . . . . . . . . . Global . . . . . . . Support . . . . . . . . . Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 ............ 16.1. Gathering Required Information 98 Background Information 98 Diagnostics 98 Account and Contact Information 98 Issue Severity 99 16.2. Escalating an Issue 99 16.3. Re-opening a Service Request 100 16.4. Additional Resources 100 Online Documentation 100 .Changes . . . . . . . . . in . . .Version . . . . . . . .2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 ............. A.1. Changes in Eclipse 101 A.1.1. Changes Since Red Hat Developer T oolset 2.0 101 A.2. Changes in GCC 101 A.3. Changes in elfutils 102 A.3.1. Changes Since Red Hat Developer T oolset 2.0 102 A.4. Changes in Git 102 A.4.1. Changes Since Red Hat Enterprise Linux 6.5 103 General Changes in the Git Suite 103 T he git am Command 104 T he git apply Command 104 T he git archive Command 104 T he git bisect Command 104 T he git blame Command 105 4 Table of Contents T he git branch Command T he git checkout Command T he git check-attr Command T he git cherry-pick Command T he git clean Command T he git clone Command T he git commit Command T he git count-objects Command T he git cvsimport Command T he git cvsserver Command T he git daemon Command T he git describe Command T he git diff Command T he git fetch Command T he git format-patch Command T he git for-each-ref Command T he git grep Command T he git hash-object Command T he git help Command T he git imap-send Command T he git init Command T he git log Command T he git ls-remote Command T he git merge Command T he git mergetool Command T he git merge-base Command T he git merge-file Command T he git notes Command T he git notes prune Subcommand T he git pull Command T he git push Command T he git read-tree Command T he git rebase Command T he git remote Command T he git replace Command T he git rerere Command T he git reset Command T he git revert Command T he git send-email Command T he git show Command T he git show-ref Command T he git stash Command T he git status Command T he git submodule Command T he git tag Command T he gitweb Interface Other new subcommands and exotic option combinations A.5. Changes in GDB A.5.1. Changes Since Red Hat Developer T oolset 2.0 A.6. Changes in Valgrind A.6.1. Changes Since Red Hat Developer T oolset 2.0 A.7. Changes in OProfile A.7.1. Changes Since Red Hat Developer T oolset 2.0 105 105 106 106 106 106 107 107 107 108 108 108 108 109 109 110 110 111 111 111 111 111 112 112 113 113 113 113 113 114 114 114 114 115 115 115 115 115 115 116 116 116 116 117 117 117 117 118 118 118 118 118 118 .Changes . . . . . . . . . in . . .Version . . . . . . . .2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 ............. B.1. Changes in Eclipse 119 5 Red Hat D eveloper Toolset 2.x User Guide B.1.1. Changes Since Red Hat Enterprise Linux 6.4 B.2. Changes in GCC B.2.1. Changes Since Red Hat Developer T oolset 1.1 B.2.1.1. Caveats Aggressive Loop Optimizations B.2.1.2. General Improvements and Changes New Local Register Allocator AddressSanitizer T hreadSanitizer Compiling Extremely Large Functions New -Og Optimization Level Caret Diagnostic Messages New -fira-hoist-pressure Option New -fopt-info Option New -floop-nest-optimize Option Hot and Cold Attributes on Labels B.2.1.3. Debugging Enhancements DWARF4 New -gsplit-dwarf Option B.2.1.4. C++ Changes Experimental C++ Features from an Upcoming Standard New thread_local Keyword Dynamic Initialization of T hread-local Variables C++11 Attribute Syntax C++11 Alignment Specifier B.2.1.5. Fortran Changes B.2.1.5.1. Caveats B.2.1.5.2. ABI Compatibility B.2.1.5.3. Other Changes BACKT RACE Intrinsic Floating Point Numbers with “q” as Exponential GFORT RAN_T MPDIR Environment Variable Fortran 2003 T S 29113 B.2.1.6. x86-specific Improvements New Instructions New Built-in Functions to Detect Run-time CPU T ype and ISA Function Multiversioning New RT M and HLE Intrinsics T ransactions Using T ransactional Synchronization Extensions Support for AMD Family 15h Processors Support for AMD Family 16h Processors B.2.2. Changes Since Red Hat Enterprise Linux 6.4 and 5.9 B.2.2.1. Status and Features B.2.2.1.1. C++11 B.2.2.1.2. C11 B.2.2.1.3. Parallelism and Concurrency C++11 T ypes and GCC Built-ins for Atomic Memory Access T ransactional Memory B.2.2.1.4. Architecture-specific Options B.2.2.1.5. Link-time Optimization B.2.2.1.6. Miscellaneous B.2.2.2. Language Compatibility B.2.2.2.1. C Duplicate Member 6 119 120 120 120 120 121 121 121 121 121 121 121 122 122 122 122 122 122 122 123 123 123 123 123 124 124 124 124 124 124 124 124 125 125 125 125 125 126 126 127 127 127 127 127 127 128 128 128 129 130 132 132 133 133 133 Table of Contents B.2.2.2.2. C++ Header Dependency Changes Name Lookup Changes Uninitialized const Visibility of T emplate Instantiations User-defined Literal Support T aking the Address of T emporary Miscellaneous B.2.2.2.3. C/C++ Warnings B.2.2.2.4. Fortran B.2.2.2.4.1. New Features B.2.2.2.4.2. Compatibility Changes B.2.2.2.4.3. Fortran 2003 Features B.2.2.2.4.4. Fortran 2003 Compatibility B.2.2.2.4.5. Fortran 2008 Features B.2.2.2.4.6. Fortran 2008 Compatibility B.2.2.2.4.7. Fortran 77 Compatibility B.2.2.3. ABI Compatibility B.2.2.3.1. C++ ABI B.2.2.3.2. Miscellaneous B.2.2.4. Debugging Compatibility B.2.2.5. Other Compatibility B.3. Changes in binutils B.3.1. GNU Linker B.3.1.1. New Features Changes Since Red Hat Enterprise Linux 6.4 Changes Since Red Hat Enterprise Linux 5.9 B.3.1.2. Compatibility Changes Changes Since Red Hat Enterprise Linux 6.4 Changes Since Red Hat Enterprise Linux 5.9 B.3.2. GNU Assembler B.3.2.1. New Features Changes Since Red Hat Enterprise Linux 6.4 Changes Since Red Hat Enterprise Linux 5.9 B.3.3. Other Binary T ools B.3.3.1. New Features Changes Since Red Hat Developer T oolset 1.1 Changes Since Red Hat Enterprise Linux 6.4 Changes Since Red Hat Enterprise Linux 5.9 B.3.3.2. Compatibility Changes Changes Since Red Hat Enterprise Linux 5.9 B.4. Changes in elfutils B.4.1. Changes Since Red Hat Developer T oolset 1.1 B.4.2. Changes Since Red Hat Enterprise Linux 6.4 B.4.3. Changes Since Red Hat Enterprise Linux 5.9 B.5. Changes in dwz B.5.1. Changes Since Red Hat Developer T oolset 1.1 B.6. Changes in GDB B.6.1. Changes Since Red Hat Developer T oolset 1.1 B.6.2. Changes Since Red Hat Enterprise Linux 6.4 New Features Compatibility Changes B.6.3. Changes Since Red Hat Enterprise Linux 5.9 New Features B.7. Changes in strace 133 133 134 135 135 135 136 136 136 137 137 138 139 139 140 141 141 141 141 142 142 142 142 143 143 143 143 144 144 144 145 145 145 145 146 146 146 146 146 147 147 147 147 148 148 149 149 149 149 152 152 156 157 157 160 7 Red Hat D eveloper Toolset 2.x User Guide B.7.1. Changes Since Red Hat Enterprise Linux 6.4 and 5.9 B.8. Changes in SystemT ap B.8.1. Changes Since Red Hat Developer T oolset 1.1 B.9. Changes in OProfile B.9.1. Changes Since Red Hat Developer T oolset 1.1 B.9.2. Changes Since Red Hat Enterprise Linux 5.9 B.10. Changes in Valgrind B.10.1. Changes Since Red Hat Developer T oolset 1.1 B.10.2. Changes Since Red Hat Enterprise Linux 5.9 160 160 160 161 161 161 162 162 162 . . . . . . . . . .History Revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164 ............. .Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164 ............. A 164 B 164 C 165 D 165 E 166 F 168 G 168 H 170 L 170 M 170 N 170 O 170 R 172 S 172 V 174 8 Table of Contents 9 Red Hat D eveloper Toolset 2.x User Guide Preface 1. Document Conventions T his manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information. In PDF and paper editions, this manual uses typefaces drawn from the Liberation Fonts set. T he Liberation Fonts set is also used in HT ML editions if the set is installed on your system. If not, alternative but equivalent typefaces are displayed. Note: Red Hat Enterprise Linux 5 and later include the Liberation Fonts set by default. 1.1. Typographic Conventions Four typographic conventions are used to call attention to specific words and phrases. T hese conventions, and the circumstances they apply to, are as follows. Mono-spaced Bold Used to highlight system input, including shell commands, file names and paths. Also used to highlight keys and key combinations. For example: T o see the contents of the file m y_next_bestselling_novel in your current working directory, enter the cat m y_next_bestselling_novel command at the shell prompt and press Enter to execute the command. T he above includes a file name, a shell command and a key, all presented in mono-spaced bold and all distinguishable thanks to context. Key combinations can be distinguished from an individual key by the plus sign that connects each part of a key combination. For example: Press Enter to execute the command. Press Ctrl+Alt+F2 to switch to a virtual terminal. T he first example highlights a particular key to press. T he second example highlights a key combination: a set of three keys pressed simultaneously. If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in m ono-spaced bold. For example: File-related classes include filesystem for file systems, file for files, and dir for directories. Each class has its own associated set of permissions. Proportional Bold T his denotes words or phrases encountered on a system, including application names; dialog-box text; labeled buttons; check-box and radio-button labels; menu titles and submenu titles. For example: Choose System → Preferences → Mouse from the main menu bar to launch Mouse Preferences. In the Buttons tab, select the Left-handed m ouse check box and click Close to switch the primary mouse button from the left to the right (making the mouse suitable for use in the left hand). T o insert a special character into a gedit file, choose Applications → Accessories → 10 Preface Character Map from the main menu bar. Next, choose Search → Find… from the Character Map menu bar, type the name of the character in the Search field and click Next. T he character you sought will be highlighted in the Character T able. Double-click this highlighted character to place it in the T ext to copy field and then click the Copy button. Now switch back to your document and choose Edit → Paste from the gedit menu bar. T he above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in proportional bold and all distinguishable by context. Mono-spaced Bold Italic or Proportional Bold Italic Whether mono-spaced bold or proportional bold, the addition of italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example: T o connect to a remote machine using ssh, type ssh username@ domain.name at a shell prompt. If the remote machine is exam ple.com and your username on that machine is john, type ssh john@ exam ple.com . T he m ount -o rem ount file-system command remounts the named file system. For example, to remount the /hom e file system, the command is m ount -o rem ount /hom e. T o see the version of a currently installed package, use the rpm -q package command. It will return a result as follows: package-version-release. Note the words in bold italics above: username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system. Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example: Publican is a DocBook publishing system. 1.2. Pull-quote Conventions T erminal output and source code listings are set off visually from the surrounding text. Output sent to a terminal is set in m ono-spaced rom an and presented thus: books books_tests Desktop Desktop1 documentation downloads drafts images mss notes photos scripts stuff svgs svn Source-code listings are also set in m ono-spaced rom an but add syntax highlighting as follows: 11 Red Hat D eveloper Toolset 2.x User Guide static int kvm_vm_ioctl_deassign_device(struct kvm *kvm, struct kvm_assigned_pci_dev *assigned_dev) { int r = 0; struct kvm_assigned_dev_kernel *match; mutex_lock(&kvm->lock); match = kvm_find_assigned_dev(&kvm->arch.assigned_dev_head, assigned_dev->assigned_dev_id); if (!match) { printk(KERN_INFO "%s: device hasn't been assigned before, " "so cannot be deassigned\n", __func__); r = -EINVAL; goto out; } kvm_deassign_device(kvm, match); kvm_free_assigned_device(kvm, match); out: mutex_unlock(&kvm->lock); return r; } 1.3. Notes and Warnings Finally, we use three visual styles to draw attention to information that might otherwise be overlooked. Note Notes are tips, shortcuts or alternative approaches to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier. Important Important boxes detail things that are easily missed: configuration changes that only apply to the current session, or services that need restarting before an update will apply. Ignoring a box labeled “Important” will not cause data loss but may cause irritation and frustration. Warning Warnings should not be ignored. Ignoring warnings will most likely cause data loss. 2. Getting Help and Giving Feedback 2.1. Do You Need Help? If you experience difficulty with a procedure described in this documentation, visit the Red Hat Customer 12 Preface Portal at http://access.redhat.com. T hrough the customer portal, you can: search or browse through a knowledgebase of technical support articles about Red Hat products. submit a support case to Red Hat Global Support Services (GSS). access other product documentation. Red Hat also hosts a large number of electronic mailing lists for discussion of Red Hat software and technology. You can find a list of publicly available mailing lists at https://www.redhat.com/mailman/listinfo. Click on the name of any mailing list to subscribe to that list or to access the list archives. 2.2. We Need Feedback! If you find a typographical error in this manual, or if you have thought of a way to make this manual better, we would love to hear from you! Please submit a report in Bugzilla: http://bugzilla.redhat.com/ against the product Red Hat Developer T oolset. When submitting a bug report, be sure to mention the manual's identifier: doc-User_Guide If you have a suggestion for improving the documentation, try to be as specific as possible when describing it. If you have found an error, please include the section number and some of the surrounding text so we can find it easily. 13 Red Hat D eveloper Toolset 2.x User Guide Part I. Introduction 14 Chapter 1. Red Hat D eveloper Toolset Chapter 1. Red Hat Developer Toolset 1.1. About Red Hat Developer Toolset Red Hat Developer T oolset is a Red Hat offering for developers on the Red Hat Enterprise Linux platform, and provides a complete set of development and performance analysis tools that can be installed and used on multiple versions of Red Hat Enterprise Linux. Executables built with the Red Hat Developer T oolset toolchain can then also be deployed and run on multiple versions of Red Hat Enterprise Linux. For detailed compatibility information, see Section 1.3, “Compatibility”. Red Hat Developer T oolset does not replace the default system tools provided with Red Hat Enterprise Linux 5 or 6 when installed on those platforms. Instead, a parallel set of developer tools provides an alternative, newer version of those tools for optional use by developers. T he default compiler and debugger, for example, remain those provided by the base Red Hat Enterprise Linux system. 15 Red Hat D eveloper Toolset 2.x User Guide T able 1.1. Red Hat Developer T oolset Components Name Version Platforms Description Eclipse 4.3.1 Red Hat Enterprise Linux 6 An integrated development environment for the graphical user interface. [a] GCC 4.8.2 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A portable compiler suite with support for C, C++, and Fortran. binutils 2.23.52 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A collection of binary tools and other utilities to inspect and manipulate object files and binaries. elfutils 0.157 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A collection of binary tools and other utilities to inspect and manipulate ELF files. dwz 0.11 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A tool to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size. Git 1.8.4 Red Hat Enterprise Linux 6 A distributed revision control system with a peer-to-peer architecture. GDB 7.6.1 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A command line debugger for programs written in C, C++, and Fortran. strace 4.7 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A debugging tool to monitor system calls that a program uses and signals it receives. memstomp 0.1.4 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A debugging tool to identify calls to library functions with overlapping memory regions that are not allowed by various standards. SystemT ap 2.1 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A tracing and probing tool to monitor the activities of the entire system without the need to instrument, recompile, install, and reboot. Valgrind 3.8.1 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 An instrumentation framework and a number of tools to profile applications in order to detect memory errors, identify memory management problems, and report any use of improper arguments in system calls. OProfile 0.9.8 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A system-wide profiler that uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system. Dyninst 8.0 Red Hat Enterprise Linux 5, Red Hat Enterprise Linux 6 A library for instrumenting and working with user-space executables during their execution. [a] If yo u intend to d evelo p ap p lic atio ns fo r Red Hat JBo s s Mid d leware o r req uire s up p o rt fo r O p enShift To o ls , it is rec o mmend ed that yo u us e Red Hat JBo s s Develo p er Stud io . Red Hat Developer T oolset differs from “T echnology Preview” compiler releases previously supplied in 16 Chapter 1. Red Hat D eveloper Toolset Red Hat Enterprise Linux in two important respects: 1. Red Hat Developer T oolset can be used on multiple major and minor releases of Red Hat Enterprise Linux, as detailed in Section 1.3, “Compatibility”. 2. Unlike T echnology Preview compilers and other tools shipped in earlier Red Hat Enterprise Linux, Red Hat Developer T oolset is fully supported under Red Hat Enterprise Linux Subscription Level Agreements, is functionally complete, and is intended for production use. Important bug fixes and security errata are issued to Red Hat Developer T oolset subscribers in a similar manner to Red Hat Enterprise Linux for two years from the release of each major version release. A new major version of Red Hat Developer T oolset is released annually, providing significant updates for existing components and adding major new components. A single minor release, issued six months after each new major version release, provides a smaller update of bug fixes, security errata, and new minor components. Additionally, the Red Hat Enterprise Linux Application Compatibility Specification also applies to Red Hat Developer T oolset (subject to some constraints on the use of newer C++11 language features, detailed in Section B.2.2.3, “ABI Compatibility”). Important Applications and libraries provided by Red Hat Developer T oolset do not replace the Red Hat Enterprise Linux system versions, nor are they used in preference to the system versions. Using a framework called Software Collections, an additional set of developer tools is installed into the /opt directory and is explicitly enabled by the user on demand using the supplied scl utility. 1.2. Main Features T he Red Hat Developer T oolset version of the GNU Compiler Collection (GCC) provides the following features: A new register allocator (LRA) has been added, improving code performance. A fast memory error detector called AddressSanitizer has been added. A fast data race detector called T hreadSanitizer has been added. Extremely large functions can now be compiled faster using less memory. A new general optimization level has been introduced. GCC diagnostic messages now highlight the exact problem in the source code. Various new optimization options have been added. DWARF4 is now used as the default debug format. GCC now fully implements the C++11 language standard. C++11 library support has been extended though is still experimental. GCC now supports dynamic initialization of thread-local variables. Support has been added for Intel FXSR, XSAVE, and XSAVEOPT instructions. New built-in functions added to detect run-time Intel CPU T ype and ISA. Intel function multi-versioning support added. Intel RT M/HLE intrinsics, built-ins, and code generation have been added. T ransactions (the -fgnu-tm option) can now be run using Intel T SX extensions. Support for AMD family 15h and 16h processors has been added. 17 Red Hat D eveloper Toolset 2.x User Guide Various Fortran changes have been included. T he version of the GNU Debugger (GDB) included in Red Hat Developer T oolset provides the following features: Improved and expanded support for Python scripting. Improved handling of C++ debugee executables. Improved inferior control commands. Improved support for ambiguous line specifications. Improved tracepoint support. Multi-program debugging. Additionally, the Red Hat Developer T oolset version of binutils provides these features: T he new gold linker, which is smaller and faster than ld. Note that gold is not the default linker and must be explicitly enabled by using the alternatives command. Support for link-time optimization (LT O) in conjunction with GCC. Support for build-IDs, unique numbers to identify executables. Support for the IFUNC and UNIQUE symbols that are used by glibc to improve performance. Due to dependencies on a particular version of the glibc library, these symbols are only available on Red Hat Enterprise Linux 6. Compressed debug sections for smaller debug info files. For a full list of changes and features introduced in this release, see Appendix A, Changes in Version 2.1. 1.3. Compatibility Red Hat Developer T oolset 2.1 is available for Red Hat Enterprise Linux 5 and 6, both for 32-bit and 64bit Intel and AMD architectures. Figure 1.1, “Red Hat Developer T oolset 2.1 Compatibility Matrix” illustrates the support for binaries built with Red Hat Developer T oolset on a certain version of Red Hat Enterprise Linux when those binaries are run on various other versions of this system. For ABI compatibility information, see Section B.2.2.3, “ABI Compatibility”. Figure 1.1. Red Hat Developer T oolset 2.1 Compatibility Matrix 18 Chapter 1. Red Hat D eveloper Toolset 1.4. Getting Access to Red Hat Developer Toolset Red Hat Developer T oolset is an offering that is distributed as part of the developer subscriptions listed in T able 1.2, “Subscriptions T hat Provide Red Hat Developer T oolset”. Depending on the subscription management service with which you registered your Red Hat Enterprise Linux system, you can either enable Red Hat Developer T oolset by using the Red Hat Subscription Management, or by using RHN Classic. For detailed instructions on how to enable Red Hat Developer T oolset using RHN Classic or Red Hat Subscription Management, see the respective section below. For information on how to register your system with one of these subscription management services, see the Red Hat Subscription Management Guide. Important If you are running a version of Red Hat Enterprise Linux prior to 5.9 or 6.4, you will be unable to download Red Hat Developer T oolset through Red Hat Subscription Management. T o obtain Red Hat Developer T oolset, you will need to either update to Red Hat Enterprise Linux 5.9 or 6.4, or register your system with RHN Classic. For more information, see https://access.redhat.com/site/solutions/129003. T able 1.2. Subscriptions T hat Provide Red Hat Developer T oolset SKU Subscription Name RH2282403 Red Hat Enterprise Linux Developer Support, Professional RH2264664 Red Hat Enterprise Linux Developer Support, Enterprise RH2262474 Red Hat Enterprise Linux Developer Suite RH3482727 Red Hat Enterprise Linux Developer Workstation, Professional RH3413336 Red Hat Enterprise Linux Developer Workstation, Enterprise RH3414706 30 day Self-Supported Red Hat Enterprise Linux Developer Workstation Evaluation RH3474212 60 day Supported Red Hat Enterprise Linux Developer Workstation Evaluation RH3437268 90 day Supported Red Hat Enterprise Linux Developer Workstation Evaluation SER0402 1-year Unsupported Partner Evaluation Red Hat Enterprise Linux SER0403 1-year Unsupported Red Hat Advanced Partner Subscription 1.4.1. Using RHN Classic If your system is registered with RHN Classic, complete the following steps to subscribe to Red Hat Developer T oolset: 1. Determine the exact name of the Red Hat Developer T oolset channel. T o do so, type the following at a shell prompt as root to display a list of all channels that are available to you: rhn-channel --available-channels 19 Red Hat D eveloper Toolset 2.x User Guide T he name of the channel depends on the specific version of Red Hat Enterprise Linux you are using and is in the following format: rhel-architecture-variant-dts2-version In addition, certain packages such as devtoolset-2-git or devtoolset-2-gcc-plugin-devel depend on packages that are only available in the Optional channel. T he name of this channel uses the following format: rhel-architecture-variant-optional-version Replace architecture with the system's CPU architecture (x86_64 or i386), variant with the Red Hat Enterprise Linux system variant (server or workstation), and version with the Red Hat Enterprise Linux system version (5 or 6). 2. Subscribe the system to the channels from Step 1 by running the following command as root: rhn-channel --add --channel=channel_name Replace channel_name with the name of the channel to enable. 3. T o verify the list of channels you are subscribed to, at any time, run as root: rhn-channel --list Once the system is subscribed, you can install Red Hat Developer T oolset as described in Section 1.5, “Installing Red Hat Developer T oolset”. For more information on how to register your system with RHN Classic, see the Red Hat Subscription Management Guide. 1.4.2. Using Red Hat Subscription Management If your system is registered with Red Hat Subscription Management, complete the following steps to attach a subscription that provides access to the repository for Red Hat Developer T oolset, and then enable that repository: 1. Determine the pool ID of a subscription that provides Red Hat Developer T oolset. T o do so, type the following at a shell prompt as root to display a list of all subscriptions that are available for your system: subscription-manager list --available For each available subscription, this command displays its name, unique identifier, expiration date, and other details related to your subscription. T he pool ID is listed on a line beginning with Pool Id. For a complete list of subscriptions that provide access to Red Hat Developer T oolset, see T able 1.2, “Subscriptions T hat Provide Red Hat Developer T oolset”. 2. Attach the appropriate subscription to your system by running the following command as root: subscription-manager subscribe --pool=pool_id Replace pool_id with the pool ID you determined in the previous step. T o verify the list of subscriptions your system has currently attached, at any time, run as root: subscription-manager list --consumed 20 Chapter 1. Red Hat D eveloper Toolset 3. Determine the exact name of Red Hat Developer T oolset repositories. T o do so, type the following at a shell prompt as root to retrieve repository metadata and to display a list of available Yum repositories: subscription-manager repos --list T he repository names depend on the specific version of Red Hat Enterprise Linux you are using, and are in the following format: rhel-variant-dts2-version-rpms rhel-variant-dts2-version-debug-rpms rhel-variant-dts2-version-source-rpms In addition, certain packages such as devtoolset-2-git or devtoolset-2-gcc-plugin-devel depend on packages that are only available in the Optional channel. T he repository names with these packages use the following format: rhel-version-variant-optional-rpms rhel-version-variant-optional-debug-rpms rhel-version-variant-optional-source-rpms Replace variant with the Red Hat Enterprise Linux system variant (server or workstation), and version with the Red Hat Enterprise Linux system version (5 or 6). 4. Enable the repositories from Step 3 by running the following command as root: subscription-manager repos --enable repository Replace repository with the name of the repository to enable. Once the subscription is attached to the system, you can install Red Hat Developer T oolset as described in Section 1.5, “Installing Red Hat Developer T oolset”. For more information on how to register your system using Red Hat Subscription Management and associate it with subscriptions, see the Red Hat Subscription Management Guide. 1.5. Installing Red Hat Developer Toolset Red Hat Developer T oolset is distributed as a collection of RPM packages that can be installed, updated, uninstalled, and inspected by using the standard package management tools that are included in Red Hat Enterprise Linux. Note that a valid subscription is required in order to install Red Hat Developer T oolset on your system. For detailed instructions on how to associate your system with an appropriate subscription and get access to the product, see Section 1.4, “Getting Access to Red Hat Developer T oolset”. Important Before installing Red Hat Developer T oolset on a system that is already running the previous version of the product, make sure that the devtoolset-1.1-gcc-debuginfo is not installed. T o uninstall this package from the system, type the following at a shell prompt as root: yum remove devtoolset-1.1-gcc-debuginfo 21 Red Hat D eveloper Toolset 2.x User Guide Important After installing Red Hat Developer T oolset, it is recommended to apply all available Red Hat Enterprise Linux errata updates to enable all Red Hat Developer T oolset features and apply fixes that may otherwise impact the tools or built code. 1.5.1. Installing All Available Components T o install all components that are included in this product, install the devtoolset-2 package by typing the following at a shell prompt as root: yum install devtoolset-2 T his installs the Eclipse development environment, all development, debugging, and performance monitoring tools, the scl utility and other dependent packages to the system. Alternatively, you can choose to install only a selected package group as described in Section 1.5.2, “Installing Individual Package Groups”. 1.5.2. Installing Individual Package Groups T o make it easier to install only certain components such as the integrated development environment or the software development toolchain, Red Hat Developer T oolset is distributed with a number of meta packages that allow you to install selected package groups as described in T able 1.3, “Red Hat Developer T oolset Meta Packages”. T able 1.3. Red Hat Developer T oolset Meta Packages Package Name Description Installed Components devtoolset-2-ide Integrated Development Environment Eclipse devtoolset-2-perftools Performance monitoring tools SystemT ap, Valgrind, OProfile, Dyninst devtoolset-2-toolchain Development and debugging tools GCC, GDB, binutils, elfutils, dwz, memstomp, strace devtoolset-2-vc Revision control systems Git T o install any of these meta packages, type the following at a shell prompt as root: yum install package_name... Replace package_name with a space-separated list of meta packages you want to install. For example, to install only the Eclipse development environment and packages that depend on it, type as root: ~]# yum install devtoolset-2-ide Alternatively, you can choose to install all available components as described in Section 1.5.1, “Installing All Available Components”. 1.5.3. Installing Optional Packages Red Hat Developer T oolset is distributed with a number of optional packages that are not installed by 22 Chapter 1. Red Hat D eveloper Toolset default. T o list all Red Hat Developer T oolset packages that are available to you but not installed on your system, type the following command at a shell prompt: yum list available devtoolset-2-\* T o install any of these optional packages, run as root: yum install package_name... Replace package_name with a space-separated list of packages that you want to install. For example, to install the devtoolset-2-gdb-gdbserver and devtoolset-2-gdb-doc packages, type: ~]# yum install devtoolset-2-gdb-gdbserver devtoolset-2-gdb-doc 1.5.4. Installing Debugging Information T o install debugging information for any of the Red Hat Developer T oolset packages, make sure that the yum-utils package is installed and run the following command as root: debuginfo-install package_name For example, to install debugging information for the devtoolset-2-dwz package, type: ~]# debuginfo-install devtoolset-2-dwz Note that in order to use this command, you need to have access to the repository with these packages. If your system is registered with Red Hat Subscription Management, enable the rhel-variantdts2-version-debug-rpm s repository as described in Section 1.4.2, “Using Red Hat Subscription Management”. If your system is registered with RHN Classic, subscribe the system to the rhel-architecture-variant-version-debuginfo channel as described in Section 1.4.1, “Using RHN Classic”. For more information on how to get access to debuginfo packages, see https://access.redhat.com/site/solutions/9907. 1.6. Updating Red Hat Developer Toolset 1.6.1. Updating to a Minor Version When a new minor version of Red Hat Developer T oolset is available, run the following command as root to update your Red Hat Enterprise Linux installation: yum update T his updates all packages on your Red Hat Enterprise Linux system, including the Red Hat Developer T oolset versions the Eclipse development environment, development, debugging, and performance monitoring tools, the scl utility and other dependent packages. 23 Red Hat D eveloper Toolset 2.x User Guide Important Use of Red Hat Developer T oolset requires the removal of any earlier pre-release versions of this product. Additionally, it is not possible to update to Red Hat Developer T oolset 2.1 from a prerelease version of Red Hat Developer T oolset, including beta releases. If you have previously installed any pre-release version of Red Hat Developer T oolset, uninstall it from your system as described in Section 1.7, “Uninstalling Red Hat Developer T oolset” and install the new version as documented in Section 1.5, “Installing Red Hat Developer T oolset”. 1.6.2. Updating to a Major Version When a new major version of Red Hat Developer T oolset is available, you can install it in parallel with the previous version of the product. For detailed instructions on how to install Red Hat Developer T oolset on your system, see Section 1.5, “Installing Red Hat Developer T oolset”. 1.7. Uninstalling Red Hat Developer Toolset T o uninstall Red Hat Developer T oolset packages from your system, type the following at a shell prompt as root: yum remove devtoolset-2\* T his removes the GNU Compiler Collection, GNU Debugger, binutils, and other packages that are part of Red Hat Developer T oolset from the system. T o uninstall the scl utility as well, type as root: yum remove scl-utils\* Note that uninstallation of the tools provided by Red Hat Developer T oolset does not affect the Red Hat Enterprise Linux system versions of these tools. For information on how to uninstall Red Hat Developer T oolset 1.1, see the Red Hat Developer T oolset 1.1 User Guide. 1.8. Additional Resources For more information about Red Hat Developer T oolset and Red Hat Enterprise Linux, see the resources listed below. Online Documentation Red Hat Subscription Management Guide — T he Red Hat Subscription Management Guide provides detailed information on how to manage subscriptions on Red Hat Enterprise Linux. Red Hat Developer T oolset 2.1 Release Notes — T he Release Notes for Red Hat Developer T oolset 2.1 contain more information about this product. Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides more information on the Eclipse IDE, libraries and runtime support, compiling and building, debugging, and profiling on this system. Red Hat Enterprise Linux 6 Installation Guide — T he Installation Guide for Red Hat Enterprise Linux 6 explains how to obtain, install, and update the system. Red Hat Enterprise Linux 5 Installation Guide — T he Installation Guide for Red Hat Enterprise Linux 24 Chapter 1. Red Hat D eveloper Toolset 5 explains how to obtain, install, and update the system. Red Hat Enterprise Linux 6 Deployment Guide — T he Deployment Guide for Red Hat Enterprise Linux 6 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 6. Red Hat Enterprise Linux 5 Deployment Guide — T he Deployment Guide for Red Hat Enterprise Linux 5 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 5. See Also Appendix A, Changes in Version 2.1 provides a comprehensive list of changes and improvements over the Red Hat Enterprise Linux system versions of the GNU Compiler Collection, GNU Debugger, and binutils, as well as information about the language, ABI, and debugging compatibility. 25 Red Hat D eveloper Toolset 2.x User Guide Part II. Integrated Development Environments 26 Chapter 2. Eclipse Chapter 2. Eclipse Eclipse is a powerful development environment that provides tools for each phase of the development process. It integrates a variety of disparate tools into a unified environment to create a rich development experience, provides a fully configurable user interface, and features a pluggable architecture that allows for extension in a variety of ways. For instance, the Valgrind plug-in allows programmers to perform memory profiling, otherwise performed on the command line, through the Eclipse user interface. Figure 2.1. Sample Eclipse Session Eclipse provides a graphical development environment alternative to traditional interaction with command line tools and as such, it is a welcome alternative to developers who do not want to use the command line interface. T he traditional, mostly command line based Linux tools suite (such as gcc or gdb) and Eclipse offer two distinct approaches to programming. Red Hat Developer T oolset is distributed with Eclipse 4 .3.1, which is based on the Eclipse Foundation's 2013 Eclipse Kepler 4.3 Service Release 1. Note that if you intend to develop applications for Red Hat JBoss Middleware or require support for OpenShift T ools, it is recommended that you use Red Hat JBoss Developer Studio. 27 Red Hat D eveloper Toolset 2.x User Guide T able 2.1. Eclipse Components Included in Red Hat Developer T oolset Package Description devtoolset-2-eclipse-cdt T he C/C++ Development T ooling (CDT ), which provides features and plug-ins for development in C and C++. devtoolset-2-eclipse-emf T he Eclipse Modeling Framework (EMF), which allows you to build applications based on a structured data model. devtoolset-2-eclipse-gef T he Graphical Editing Framework (GEF), which allows you to create a rich graphical editor from an existing application model. devtoolset-2-eclipse-rse T he Remote System Explorer (RSE) framework, which allows you to work with remote systems from Eclipse. devtoolset-2-eclipse-jgit JGit, a Java implementation of the Git revision control system. devtoolset-2-eclipse-egit EGit, a team provider for Eclipse that provides features and plugins for interaction with Git repositories. devtoolset-2-eclipse-mylyn Mylyn, a task management system for Eclipse. devtoolset-2-eclipse-linuxtools A meta package for Linux-specific Eclipse plug-ins. devtoolset-2-eclipse-changelog [a] T he ChangeLog plug-ins, which allows you to create and maintain changelog files. devtoolset-2-eclipse-gcov[a] T he GCov plug-in, which integrates the GCov test coverage program with Eclipse. devtoolset-2-eclipse-gprof[a] T he Gprof plug-in, which integrates the Gprof performance analysis utility with Eclipse. devtoolset-2-eclipse-manpage[a] T he Man Page plug-in, which allows you to view manual pages in Eclipse. devtoolset-2-eclipse-oprofile[a] T he OProfile plug-in, which integrates OProfile with Eclipse. devtoolset-2-eclipse-perf[a] T he Perf plug-in, which integrates the perf tool with Eclipse. devtoolset-2-eclipse-rpm-editor[a] T he Eclipse Spec File Editor, which allows you to maintain RPM spec files. devtoolset-2-eclipse-rpmstubby[a] T he RPM Stubby plug-in, which allows you to generate RPM spec files. devtoolset-2-eclipse-systemtap[a] T he SystemT ap plug-in, which integrates SystemT ap with Eclipse. devtoolset-2-eclipse-valgrind[a] T he Valgrind plug-in, which integrates Valgrind with Eclipse. [a] This p ac kag e is ins talled as a d ep end enc y o f devtoolset-2-eclipse-linuxtools. 2.1. Installing Eclipse In Red Hat Developer T oolset, the Eclipse development environment is provided as a collection of RPM packages and is automatically installed with the devtoolset-2-ide package as described in Section 1.5, “Installing Red Hat Developer T oolset”. For a list of available components, see T able 2.1, “Eclipse Components Included in Red Hat Developer T oolset”. 28 Chapter 2. Eclipse Note T he Red Hat Developer T oolset version of Eclipse is only available for Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. T his version fully supports C, C++, and Java development, but does not provide support for the Fortran programming language. 2.1.1. Building Eclipse from the Source RPM Packages It is recommended that you install the Red Hat Developer T oolset version of Eclipse from the official RPM packages distributed by Red Hat. If, for some reason, you need to build Red Hat Developer T oolset 2.1 Eclipse on Red Hat Enterprise Linux 6 from the supplied source RPM (SRPM) packages, complete the following steps: 1. Install the java-1.7.0-openjdk package from Red Hat Enterprise Linux 6.3 or newer and all its dependencies. 2. Download, build, and install the maven package and all its dependencies from the SRPM packages for Fedora 19. 3. Download, build, and install the tycho package and all its dependencies from the SRPM packages for Fedora 19. 4. Download and build all dependent packages listed in the devtoolset-2-eclipse SRPM package. 5. Download and build the devtoolset-2-eclipse SRPM package. 6. Download and build additional devtoolset-2-eclipse-* SRPM packages. 2.2. Using Eclipse T o start the Red Hat Developer T oolset version of Eclipse, either select Applications → Programming → DT S Eclipse from the panel, or type the following at a shell prompt: scl enable devtoolset-2 'eclipse' During its startup, Eclipse prompts you to select a workspace, that is, a directory in which you want to store your projects. You can either use ~/workspace/, which is the default option, or click the Browse button to browse your file system and select a custom directory. Additionally, you can select the Use this as the default and do not ask again check box to prevent Eclipse from displaying this dialog box the next time you run this development environment. When you are done, click the OK button to confirm the selection and proceed with the startup. 2.2.1. Using the Red Hat Developer Toolset Toolchain T o use the Red Hat Developer T oolset version of Eclipse with support for the GNU Compiler Collection and binutils from Red Hat Developer T oolset, make sure that the devtoolset-2-toolchain package is installed and run the application as described in Section 2.2, “Using Eclipse”. Red Hat Developer T oolset Eclipse uses the Red Hat Developer T oolset toolchain by default. For detailed instructions on how to install the devtoolset-2-toolchain package in your system, see Section 1.5, “Installing Red Hat Developer T oolset”. 29 Red Hat D eveloper Toolset 2.x User Guide Important If you are working on a project that you previously built with the Red Hat Enterprise Linux version of the GNU Compiler Collection, make sure that you discard all previous build results. T o do so, open the project in Eclipse and select Project → Clean from the menu. 2.2.2. Using the Red Hat Enterprise Linux Toolchain T o use the Red Hat Developer T oolset version of Eclipse with support for the toolchain distributed with Red Hat Enterprise Linux, either uninstall devtoolset-2-gcc, devtoolset-2-binutils, and related packages from your system, or change the configuration of the project to use absolute paths to the Red Hat Enterprise Linux system versions of gcc, g++, and as. T o uninstall the Red Hat Developer T oolset toolchain from the system, type the following at a shell prompt as root: yum remove devtoolset-2-gcc\* devtoolset-2-binutils\* T o configure Eclipse to explicitly use the Red Hat Enterprise Linux system versions of the tools for the current project, complete the following steps: 1. In the C/C++ perspective, choose Project → Properties from the main menu bar to open the project properties. 2. In the menu on the left-hand side of the dialog box, click C/C++ Build → Settings. 3. Select the T ool Settings tab. 4. If you are working on a C project: a. select GCC C Compiler or Cross GCC Compiler and change the value of the Com m and field to: /usr/bin/gcc b. select GCC C Linker or Cross GCC Linker and change the value of the Com m and field to: /usr/bin/gcc c. select GCC Assembler or Cross GCC Assembler and change the value of the Com m and field to: /usr/bin/as If you are working on a C++ project: a. select GCC C++ Compiler or Cross G++ Compiler and change the value of the Com m and field to: /usr/bin/g++ b. select GCC C Compiler or Cross GCC Compiler and change the value of the Com m and field to: 30 Chapter 2. Eclipse /usr/bin/gcc c. select GCC C++ Linker or Cross G++ Linker and change the value of the Com m and field to: /usr/bin/g++ d. select GCC Assembler or Cross GCC Assembler and change the value of the Com m and field to: /usr/bin/as 5. Click the OK button to save the configuration changes. 2.3. Additional Resources A detailed description of Eclipse and all its features is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation Eclipse includes a built-in Help system which provides extensive documentation for each integrated feature and tool. T his greatly decreases the initial time investment required for new developers to become fluent in its use. T he use of this Help section is detailed in the Red Hat Enterprise Linux Developer Guide linked below. Online Documentation Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides more information on Eclipse, including a description of the user interface, overview of available development toolkits, or instructions on how to use it to build RPM packages. See Also Section A.1, “Changes in Eclipse” provides a comprehensive list of features and improvements over the Eclipse development environment included in Red Hat Enterprise Linux and the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 3, GNU Compiler Collection (GCC) provides information on how to compile programs written in C, C++, and Fortran on the command line. 31 Red Hat D eveloper Toolset 2.x User Guide Part III. Development Tools 32 Chapter 3. GNU Compiler Collection (GCC) Chapter 3. GNU Compiler Collection (GCC) T he GNU Compiler Collection, commonly abbreviated GCC, is a portable compiler suite with support for a wide selection of programming languages. Red Hat Developer T oolset is distributed with GCC 4 .8. T his version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements, including optimization for various new Intel and AMD processors, support for OpenMP 3.1 and link-time optimization. T his version also includes experimental support for the C++11 standard, C++11 atomic types, and T ransactional Memory. For a detailed list of changes, see Section B.2, “Changes in GCC”. Note T he Red Hat Developer T oolset version of the GNU Debugger is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. Notable differences are as follows: On Red Hat Enterprise Linux 6, GCC uses the ST T _GNU_UNIQUE symbol. On Red Hat Enterprise Linux 5, it does not. On Red Hat Enterprise Linux 6, GCC uses the -m arch=i686 command line option by default. On Red Hat Enterprise Linux 5, it uses the -m arch=i586 option. On Red Hat Enterprise Linux 6, GCC uses the -gdwarf-3 command line option by default. On Red Hat Enterprise Linux 5, it uses the -gdwarf-2 option. T he -fgnu89-inline command line option has different defaults on Red Hat Enterprise Linux 6 and Red Hat Enterprise Linux 5. 3.1. GNU C Compiler 3.1.1. Installing the C Compiler In Red Hat Developer T oolset, the GNU C compiler is provided by the devtoolset-2-gcc package and is automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. 3.1.2. Using the C Compiler T o compile a C program on the command line, run the gcc compiler as follows: scl enable devtoolset-2 'gcc -o output_file source_file...' T his creates a binary file named output_file in the current working directory. If the -o option is omitted, the compiler creates a file named a.out by default. When you are working on a project that consists of several source files, it is common to compile an object file for each of the source files first and then link these object files together. T his way, when you change a single source file, you can recompile only this file without having to compile the entire project. T o compile an object file on the command line, run the following command: scl enable devtoolset-2 'gcc -o object_file -c source_file' T his creates an object file named object_file. If the -o option is omitted, the compiler creates a file 33 Red Hat D eveloper Toolset 2.x User Guide named after the source file with the .o file extension. T o link object files together and create a binary file, run: scl enable devtoolset-2 'gcc -o output_file object_file...' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset gcc as default: scl enable devtoolset-2 'bash' Note T o verify the version of gcc you are using at any point, type the following at a shell prompt: which gcc Red Hat Developer T oolset's gcc executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset gcc: gcc -v Important Some newer library features are statically linked into applications built with Red Hat Developer T oolset to support execution on multiple versions of Red Hat Enterprise Linux. T his adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code. If the need for developers to rebuild their applications due to such an issue arises, Red Hat will signal this via a security erratum. Developers are strongly advised not to statically link their entire application for the same reasons. 34 Chapter 3. GNU Compiler Collection (GCC) Example 3.1. Compiling a C Program on the Command Line Consider a source file named hello.c with the following contents: #include <stdio.h> int main(int argc, char *argv[]) { printf("Hello, World!\n"); return 0; } T o compile this source code on the command line by using the gcc compiler from Red Hat Developer T oolset, type: ~]$ scl enable devtoolset-2 'gcc -o hello hello.c' T his creates a new binary file called hello in the current working directory. 3.1.3. Running a C Program When gcc compiles a program, it creates an executable binary file. T o run this program on the command line, change to the directory with the executable file and type: ./file_name Example 3.2. Running a C Program on the Command Line Assuming that you have successfully compiled the hello binary file as shown in Example 3.1, “Compiling a C Program on the Command Line”, you can run it by typing the following at a shell prompt: ~]$ ./hello Hello, World! 3.2. GNU C++ Compiler 3.2.1. Installing the C++ Compiler In Red Hat Developer T oolset, the GNU C++ compiler is provided by the devtoolset-2-gcc-c++ package and is automatically installed with the devtoolset-2-toolchain package as described in Section 1.5, “Installing Red Hat Developer T oolset”. 3.2.2. Using the C++ Compiler T o compile a C++ program on the command line, run the g++ compiler as follows: scl enable devtoolset-2 'g++ -o output_file source_file...' T his creates a binary file named output_file in the current working directory. If the -o option is 35 Red Hat D eveloper Toolset 2.x User Guide omitted, the g++ compiler creates a file named a.out by default. When you are working on a project that consists of several source files, it is common to compile an object file for each of the source files first and then link these object files together. T his way, when you change a single source file, you can recompile only this file without having to compile the entire project. T o compile an object file on the command line, run the following command: scl enable devtoolset-2 'g++ -o object_file -c source_file' T his creates an object file named object_file. If the -o option is omitted, the g++ compiler creates a file named after the source file with the .o file extension. T o link object files together and create a binary file, run: scl enable devtoolset-2 'g++ -o output_file object_file...' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset g++ as default: scl enable devtoolset-2 'bash' Note T o verify the version of g++ you are using at any point, type the following at a shell prompt: which g++ Red Hat Developer T oolset's g++ executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset g++: g++ -v Important Some newer library features are statically linked into applications built with Red Hat Developer T oolset to support execution on multiple versions of Red Hat Enterprise Linux. T his adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code. If the need for developers to rebuild their applications due to such an issue arises, Red Hat will signal this via a security erratum. Developers are strongly advised not to statically link their entire application for the same reasons. 36 Chapter 3. GNU Compiler Collection (GCC) Example 3.3. Compiling a C++ Program on the Command Line Consider a source file named hello.cpp with the following contents: #include <iostream> using namespace std; int main(int argc, char *argv[]) { cout << "Hello, World!" << endl; return 0; } T o compile this source code on the command line by using the g++ compiler from Red Hat Developer T oolset, type: ~]$ scl enable devtoolset-2 'g++ -o hello hello.cpp' T his creates a new binary file called hello in the current working directory. 3.2.3. Running a C++ Program When g++ compiles a program, it creates an executable binary file. T o run this program on the command line, change to the directory with the executable file and type: ./file_name Example 3.4 . Running a C++ Program on the Command Line Assuming that you have successfully compiled the hello binary file as shown in Example 3.3, “Compiling a C++ Program on the Command Line”, you can run it by typing the following at a shell prompt: ~]$ ./hello Hello, World! 3.3. GNU Fortran Compiler 3.3.1. Installing the Fortran Compiler In Red Hat Developer T oolset, the GNU Fortran compiler is provided by the devtoolset-2-gcc-gfortran package and is automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. 3.3.2. Using the Fortran Compiler T o compile a Fortran program on the command line, run the gfortran compiler as follows: scl enable devtoolset-2 'gfortran -o output_file source_file...' 37 Red Hat D eveloper Toolset 2.x User Guide T his creates a binary file named output_file in the current working directory. If the -o option is omitted, the compiler creates a file named a.out by default. When you are working on a project that consists of several source files, it is common to compile an object file for each of the source files first and then link these object files together. T his way, when you change a single source file, you can recompile only this file without having to compile the entire project. T o compile an object file on the command line, run the following command: scl enable devtoolset-2 'gfortran -o object_file -c source_file' T his creates an object file named object_file. If the -o option is omitted, the compiler creates a file named after the source file with the .o file extension. T o link object files together and create a binary file, run: scl enable devtoolset-2 'gfortran -o output_file object_file...' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset gfortran as default: scl enable devtoolset-2 'bash' Note T o verify the version of gfortran you are using at any point, type the following at a shell prompt: which gfortran Red Hat Developer T oolset's gfortran executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset gfortran: gfortran -v Important Some newer library features are statically linked into applications built with Red Hat Developer T oolset to support execution on multiple versions of Red Hat Enterprise Linux. T his adds a small additional security risk as normal Red Hat Enterprise Linux errata would not change this code. If the need for developers to rebuild their applications due to such an issue arises, Red Hat will signal this via a security erratum. Developers are strongly advised not to statically link their entire application for the same reasons. 38 Chapter 3. GNU Compiler Collection (GCC) Example 3.5. Compiling a Fortran Program on the Command Line Consider a source file named hello.f with the following contents: program hello print *, "Hello, World!" end program hello T o compile this source code on the command line by using the gfortran compiler from Red Hat Developer T oolset, type: ~]$ scl enable devtoolset-2 'gfortran -o hello hello.f' T his creates a new binary file called hello in the current working directory. 3.3.3. Running a Fortran Program When gfortran compiles a program, it creates an executable binary file. T o run this program on the command line, change to the directory with the executable file and type: ./file_name Example 3.6. Running a Fortran Program on the Command Line Assuming that you have successfully compiled the hello binary file as shown in Example 3.5, “Compiling a Fortran Program on the Command Line”, you can run it by typing the following at a shell prompt: ~]$ ./hello Hello, World! 3.4. Additional Resources A detailed description of the GNU Compiler Collections and its features is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation gcc(1) — T he manual page for the gcc compiler provides detailed information on its usage; with few exceptions, g++ accepts the same command line options as gcc. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man gcc' gfortran(1) — T he manual page for the gfortran compiler provides detailed information on its usage. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man gfortran' 39 Red Hat D eveloper Toolset 2.x User Guide C++ Standard Library Documentation — Documentation on the C++ standard library can be optionally installed by typing the following at a shell prompt as root: yum install devtoolset-2-libstdc++-docs Once installed, HT ML documentation is available at /opt/rh/devtoolset2/root/usr/share/doc/devtoolset-2-libstdc++-docs-4 .8.2/htm l/index.htm l. Online Documentation Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides in-depth information about GCC. Using the GNU Compiler Collection — T he official GCC manual provides an in-depth description of the GNU compilers and their usage. T he GNU C++ Library — T he GNU C++ library documentation provides detailed information about the GNU implementation of the standard C++ library. T he GNU Fortran Compiler — T he GNU Fortran compiler documentation provides detailed information on gfortran's usage. See Also Section B.2, “Changes in GCC” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of the GNU Compiler Collection and the version distributed in the previous release of Red Hat Developer T oolset, as well as information about the language, ABI, and debugging compatibility. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 2, Eclipse provides a general introduction to the Eclipse development environment, and describes how to use it with the tools from Red Hat Developer T oolset. Chapter 4, binutils explains how to use the binutils, a collection of binary tools to inspect and manipulate object files and binaries. Chapter 5, elfutils explains how to use elfutils, a collection of binary tools to inspect and manipulate ELF files. Chapter 6, dwz explains how to use dwz to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size. Chapter 8, GNU Debugger (GDB) provides information on how to debug programs written in C, C++, and Fortran. 40 Chapter 4. binutils Chapter 4. binutils binutils is a collection of various binary tools such as the GNU linker, GNU assembler, and other utilities that allow you to inspect and manipulate object files and binaries. See T able 4.1, “T ools Included in binutils for Red Hat Developer T oolset” for a complete list of binary tools that are distributed with the Red Hat Developer T oolset version of binutils. Red Hat Developer T oolset is distributed with binutils 2.23.52. T his version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements, including the new gold linker, several new command line options, improvements to the linker script language, and support for link-time optimization, compressed debug sections, and new instruction sets. For a detailed list of changes, see Section B.3, “Changes in binutils”. T able 4 .1. T ools Included in binutils for Red Hat Developer T oolset Name Description addr2line T ranslates addresses into file names and line numbers. ar Creates, modifies, and extracts files from archives. as T he GNU assembler. c++filt Decodes mangled C++ symbols. dwp Combines DWARF object files into a single DWARF package file. elfedit Examines and edits ELF files. gprof Display profiling information. ld T he GNU linker. ld.bfd An alternative to the GNU linker. ld.gold A new ELF linker. nm Lists symbols from object files. objcopy Copies and translates object files. objdum p Displays information from object files. ranlib Generates an index to the contents of an archive to make access to this archive faster. readelf Displays information about ELF files. size Lists section sizes of object or archive files. strings Displays printable character sequences in files. strip Discards all symbols from object files. 4.1. Installing binutils In Red Hat Developer T oolset, binutils are provided by the devtoolset-2-binutils package and are automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. 41 Red Hat D eveloper Toolset 2.x User Guide 4.2. Using the GNU Assembler T o produce an object file from an assembly language program, run the as tool as follows: scl enable devtoolset-2 'as [option...] -o object_file source_file' T his creates an object file named object_file in the current working directory. Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset as as default: scl enable devtoolset-2 'bash' Note T o verify the version of as you are using at any point, type the following at a shell prompt: which as Red Hat Developer T oolset's as executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset as: as -v 4.3. Using the GNU Linker T o create an executable binary file or a library from object files, run the ld tool as follows: scl enable devtoolset-2 'ld [option...] -o output_file object_file...' T his creates a binary file named output_file in the current working directory. If the -o option is omitted, the compiler creates a file named a.out by default. Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset ld as default: scl enable devtoolset-2 'bash' 42 Chapter 4. binutils Note T o verify the version of ld you are using at any point, type the following at a shell prompt: which ld Red Hat Developer T oolset's ld executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset ld: ld -v 4.4. Using Other Binary Tools T he binutils provide many binary tools other than a linker and assembler. For a complete list of these tools, see T able 4.1, “T ools Included in binutils for Red Hat Developer T oolset”. T o execute any of the tools that are part of binutils, run the command as follows: scl enable devtoolset-2 'tool [option...] file_name' See T able 4.1, “T ools Included in binutils for Red Hat Developer T oolset” for a list of tools that are distributed with binutils. For example, to use the objdum p tool to inspect an object file, type: scl enable devtoolset-2 'objdump [option...] object_file' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset binary tools as default: scl enable devtoolset-2 'bash' Note T o verify the version of binutils you are using at any point, type the following at a shell prompt: which objdump Red Hat Developer T oolset's objdum p executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset objdum p: objdump -v 4.5. Additional Resources 43 Red Hat D eveloper Toolset 2.x User Guide A detailed description of binutils is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation as(1), ld(1), addr2line(1), ar(1), c++filt(1), dwp(1), elfedit(1), gprof(1), nm(1), objcopy(1), objdump(1), ranlib(1), readelf(1), size(1), strings(1), strip(1), — Manual pages for various binutils tools provide more information about their respective usage. T o display a manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man tool' Online Documentation Documentation for binutils — T he binutils documentation provides an in-depth description of the binary tools and their usage. See Also Section B.3, “Changes in binutils” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of binutils and the version distributed in the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 5, elfutils explains how to use elfutils, a collection of binary tools to inspect and manipulate ELF files. Chapter 3, GNU Compiler Collection (GCC) provides information on how to compile programs written in C, C++, and Fortran. 44 Chapter 5. elfutils Chapter 5. elfutils elfutils is a collection of various binary tools such as eu-objdum p, eu-readelf, and other utilities that allow you to inspect and manipulate ELF files. See T able 5.1, “T ools Included in elfutils for Red Hat Developer T oolset” for a complete list of binary tools that are distributed with the Red Hat Developer T oolset version of elfutils. Red Hat Developer T oolset is distributed with elfutils 0.157. T his version is more recent than the version included in Red Hat Enterprise Linux and the previous release of Red Hat Developer T oolset, and provides numerous bug fixes and enhancements. T able 5.1. T ools Included in elfutils for Red Hat Developer T oolset Name Description eu-addr2line T ranslates addresses into file names and line numbers. eu-ar Creates, modifies, and extracts files from archives. eu-elfcm p Compares relevant parts of two ELF files for equality. eu-elflint Verifies that ELF files are compliant with the generic ABI (gABI) and processor-specific supplement ABI (psABI) specification. eu-findtextrel Locates the source of text relocations in files. eu-m ake-debugarchive Creates an offline archive for debugging. eu-nm Lists symbols from object files. eu-objdum p Displays information from object files. eu-ranlib Generates an index to the contents of an archive to make access to this archive faster. eu-readelf Displays information about ELF files. eu-size Lists section sizes of object or archive files. eu-strings Displays printable character sequences in files. eu-strip Discards all symbols from object files. eu-unstrip Combines stripped files with separate symbols and debug information. 5.1. Installing elfutils In Red Hat Developer T oolset, elfutils is provided by the devtoolset-2-elfutils package and is automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of elfutils is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. 5.2. Using elfutils T o execute any of the tools that are part of elfutils, run the command as follows: 45 Red Hat D eveloper Toolset 2.x User Guide scl enable devtoolset-2 'tool [option...] file_name' See T able 5.1, “T ools Included in elfutils for Red Hat Developer T oolset” for a list of tools that are distributed with elfutils. For example, to use the eu-objdum p tool to inspect an object file, type: scl enable devtoolset-2 'eu-objdump [option...] object_file' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset binary tools as default: scl enable devtoolset-2 'bash' Note T o verify the version of elfutils you are using at any point, type the following at a shell prompt: which eu-objdump Red Hat Developer T oolset's eu-objdum p executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset eu-objdum p: eu-objdump -V 5.3. Additional Resources A detailed description of elfutils is beyond the scope of this book. For more information, see the resources listed below. See Also Section A.3, “Changes in elfutils” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of elfutils and the version distributed in the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 3, GNU Compiler Collection (GCC) provides information on how to compile programs written in C, C++, and Fortran. Chapter 4, binutils explains how to use the binutils, a collection of binary tools to inspect and manipulate object files and binaries. Chapter 6, dwz explains how to use dwz to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size. 46 Chapter 6. dwz Chapter 6. dwz dwz is a command line tool that attempts to optimize DWARF debugging information contained in ELF shared libraries and ELF executables for size. T o do so, dwz replaces DWARF information representation with equivalent smaller representation where possible, and reduces the amount of duplication by using techniques from Appendix E of the DWARF Standard. Red Hat Developer T oolset is distributed with dwz 0.11. 6.1. Installing dwz In Red Hat Developer T oolset, the dwz utility is provided by the devtoolset-2-dwz package and is automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of dwz is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. 6.2. Using dwz T o optimize DWARF debugging information in a binary file, run the dwz tool as follows: scl enable devtoolset-2 'dwz [option...] file_name' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset dwz as default: scl enable devtoolset-2 'bash' Note T o verify the version of dwz you are using at any point, type the following at a shell prompt: which dwz Red Hat Developer T oolset's dwz executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset dwz: dwz -v 6.3. Additional Resources A detailed description of dwz and its features is beyond the scope of this book. For more information, 47 Red Hat D eveloper Toolset 2.x User Guide see the resources listed below. Installed Documentation dwz(1) — T he manual page for the dwz utility provides detailed information on its usage. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man dwz' See Also Section B.5, “Changes in dwz” provides a comprehensive list of features and enhancements over the version of dwz distributed in the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 3, GNU Compiler Collection (GCC) provides information on how to compile programs written in C, C++, and Fortran. Chapter 4, binutils explains how to use the binutils, a collection of binary tools to inspect and manipulate object files and binaries. Chapter 5, elfutils explains how to use elfutils, a collection of binary tools to inspect and manipulate ELF files. 48 Part IV. Revision Control Systems Part IV. Revision Control Systems 49 Red Hat D eveloper Toolset 2.x User Guide Chapter 7. Git Git is a distributed revision control system with a peer-to-peer architecture. As opposed to centralized version control systems with a client-server model, Git ensures that each working copy of a Git repository is its exact copy with complete revision history. T his not only allows you to work on and contribute to projects without the need to have permission to push your changes to their official repositories, but also makes it possible for you to work with no network connection. Red Hat Developer T oolset is distributed with Git 1.8.4 . T his version is more recent than the version included in Red Hat Enterprise Linux and provides a number of bug fixes and enhancements. For a detailed list of changes, see Section A.4, “Changes in Git”. 7.1. Installing Git In Red Hat Developer T oolset, the Git revision control system is provided as a collection of RPM packages and is automatically installed with the devtoolset-2-vc package as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of Git is only available for Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. 7.2. Configuring Git 7.2.1. Configuring the Default Text Editor Certain Git commands such as git com m it require the user to write a short message or make some changes in an external text editor. T o determine which text editor to start, Git attempts to read the value of the GIT _EDIT OR environment variable, the core.editor configuration option, the VISUAL environment variable, and finally the EDIT OR environment variable in this particular order. If none of these options and variables are specified, the git command starts vi as a reasonable default option. T o change the value of the core.editor configuration option in order to specify a different text editor, type the following at a shell prompt: scl enable devtoolset-2 'git config --global core.editor command' Replace command with the command to be used to start the selected text editor. Example 7.1. Configuring the Default T ext Editor T o configure Git to use vim as the default text editor, type the following at a shell prompt: ~]$ scl enable devtoolset-2 'git config --global core.editor vim' 7.2.2. Setting Up User Information In Git, each commit (or revision) is associated with the full name and email of the person responsible for 50 Chapter 7. Git it. By default, Git uses an identity based on the user name and the host name. T o change the full name associated with your Git commits, type the following at a shell prompt: scl enable devtoolset-2 'git config --global user.name "full name"' T o change the email address associated with your Git commits, type: scl enable devtoolset-2 'git config --global user.email "email_address"' Example 7.2. Setting Up User Information T o configure Git to use John Doe as your full name and john@ exam ple.com as your email address, type the following at a shell prompt: ~]$ scl enable devtoolset-2 'git config --global user.name "John Doe"' ~]$ scl enable devtoolset-2 'git config --global user.email "[email protected]"' 7.3. Using Git 7.3.1. Creating a New Repository A repository is a place where Git stores all files that are under revision control, as well as additional data related to these files, such as the complete history of changes or information about who made those changes and when. Unlike in centralized revision control systems like Subversion or CVS, a Git repository and a working directory are usually the same. A typical Git repository also only stores a single project and when publicly accessible, it allows anyone to create its clone with a complete revision history. Initializing an Empty Repository T o create a new, empty Git repository, change to the directory in which you want to keep the repository and type the following at a shell prompt: scl enable devtoolset-2 'git init' T his creates a hidden directory named .git in which all repository information is stored. Importing Data to a Repository T o put an existing project under revision control, create a Git repository in the directory with the project and run the following command: scl enable devtoolset-2 'git add .' T his marks all files and directories in the current working directory as ready to be added to the Git repository. T o proceed and actually add this content to the repository, commit the changes by typing the following at a shell prompt: scl enable devtoolset-2 'git commit [-m "commit message"]' Replace commit message with a short description of your revision. If you omit the -m option, this 51 Red Hat D eveloper Toolset 2.x User Guide command allows you to write the commit message in an external text editor. For information on how to configure the default text editor, see Section 7.2.1, “Configuring the Default T ext Editor”. 7.3.2. Cloning an Existing Repository Cloning a Git Repository T o clone an existing Git repository, type the following at a shell prompt: scl enable devtoolset-2 'git clone git_repository [directory]' Replace git_repository with a URL or a path to the Git repository you want to clone, and directory with a path to the directory in which you want to store the clone. Cloning a Subversion Repository When the devtoolset-2-git-svn package is installed in the system, Git allows you to create a Git clone of a Subversion repository. T o do so, type the following at a shell prompt: scl enable devtoolset-2 'git svn clone svn_repository [directory]' Replace svn_repository with a URL or a path to the Subversion repository you want to clone, and directory with a path to the directory in which you want to store the clone. For information on how to install the devtoolset-2-git-svn package, see Section 1.5.3, “Installing Optional Packages”. Cloning a CVS Repository When the devtoolset-2-git-cvs package is installed in the system, Git allows you to create a Git clone of a CVS repository. T o do so, change to the directory with your working copy of the CVS repository and type the following at a shell prompt: scl enable devtoolset-2 'git cvsimport -C directory cvs_module' Replace cvs_module with the name of the subdirectory in which the project is stored, and directory with a path to the directory in which you want to store the clone. For information on how to install the devtoolset-2-git-cvs package, see Section 1.5.3, “Installing Optional Packages”. 7.3.3. Adding, Renaming, and Deleting Files Adding Files and Directories T o add an existing file to a Git repository and put it under revision control, change to the directory with your local Git repository and type the following at a shell prompt: scl enable devtoolset-2 'git add file...' Replace file with the file or files you want to add. T his command marks the selected file or files as ready to be added to the Git repository. Similarly, to add all files that are stored in a certain directory to a Git repository, type: scl enable devtoolset-2 'git add directory...' 52 Chapter 7. Git Replace directory with the directory or directories you want to add. T his command marks all files in the selected directory or directories as ready to be added to the Git repository. T o proceed and actually add this content to the repository, commit the changes as described in Section 7.3.5, “Committing Changes”. Renaming Files and Directories T o rename an existing file or directory in a Git repository, change to the directory with your local Git repository and type the following at a shell prompt: scl enable devtoolset-2 'git mv old_name new_name' Replace old_name with the current name of the file or directory and new_name with the new name. T his command renames the selected file or directory and marks it as ready to be renamed in the Git repository. T o proceed and actually rename the content in the repository, commit the changes as described in Section 7.3.5, “Committing Changes”. Deleting Files and Directories T o delete an existing file from a Git repository, change to the directory with your local Git repository and type the following at a shell prompt: scl enable devtoolset-2 'git rm file...' Replace file with the file or files you want to delete. T his command deletes all selected files and marks them as ready to be deleted form the Git repository. Similarly, to delete all files that are stored in a certain directory from a Git repository, type: scl enable devtoolset-2 'git rm -r directory...' Replace directory with the directory or directories you want to delete. T his command deletes all selected directories and marks them as ready to be deleted from the Git repository. T o proceed and actually delete this content from the repository, commit the changes as described in Section 7.3.5, “Committing Changes”. 7.3.4. Viewing Changes Viewing the Current Status T o determine the current status of your local Git repository, change to the directory with the repository and type the following command at a shell prompt: scl enable devtoolset-2 'git status' T his command displays information about all uncommitted changes in the repository (new file, renam ed, deleted, or m odified) and tells you which changes will be applied the next time you commit them. For information on how to commit your changes, see Section 7.3.5, “Committing Changes”. Viewing Differences T o view all changes in a Git repository, change to the directory with the repository and type the following 53 Red Hat D eveloper Toolset 2.x User Guide at a shell prompt: scl enable devtoolset-2 'git diff' T his command displays changes between the files in the repository and their latest revision. If you are only interested in changes in a particular file, supply its name on the command line as follows: scl enable devtoolset-2 'git diff file...' Replace file with the file or files you want to view. 7.3.5. Committing Changes T o apply your changes to a Git repository and create a new revision, change to the directory with the repository and type the following command at a shell prompt: scl enable devtoolset-2 'git commit [-m "commit message"]' Replace commit message with a short description of your revision. T his command commits all changes in files that are explicitly marked as ready to be committed. T o commit changes in all files that are under revision control, add the -a command line option as follows: scl enable devtoolset-2 'git commit -a [-m "commit message"]' Note that if you omit the -m option, the command allows you to write the commit message in an external text editor. For information on how to configure the default text editor, see Section 7.2.1, “Configuring the Default T ext Editor”. 7.3.6. Sharing Changes Unlike in centralized version control systems such as CVS or Subversion, when working with Git, project contributors usually do not make their changes in a single, central repository. Instead, they either create a publicly accessible clone of their local repository, or submit their changes to others over email as patches. Pushing Changes to a Public Git Repository T o push your changes to a publicly accessible Git repository, change to the directory with your local repository and type the following at a shell prompt: scl enable devtoolset-2 'git push remote_repository' Replace remote_repository with the name of the remote repository you want to push your changes to. Note that the repository from which you originally cloned your local copy is automatically named origin. Creating Patches from Individual Commits T o create patches from your commits, change to the directory with your local Git repository and type the following at a shell prompt: scl enable devtoolset-2 'git format-patch remote_repository' Replace remote_repository with the name of the remote repository from which you made your local copy. T his creates a patch for each commit that is not present in this remote repository. 54 Chapter 7. Git 7.3.7. Updating a Git Repository T o update your local copy of a Git repository and get the latest changes from a remote repository, change to the directory with your local Git repository and type the following at a shell prompt: scl enable devtoolset-2 'git fetch remote_repository' Replace remote_repository with the name of the remote repository. T his command fetches information about the current status of the remote repository, allowing you to review these changes before applying them to your local copy. T o proceed and merge these changes with what you have in your local Git repository, type: scl enable devtoolset-2 'git merge remote_repository' Alternatively, you can perform both these steps at the same time by using the following command instead: scl enable devtoolset-2 'git pull remote_repository' 7.4. Additional Resources A detailed description of Git and its features is beyond the scope of this book. For more information about this revision control system, refer to the resources listed below. Installed Documentation gittutorial(7) — T he manual page named gittutorial provides a brief introduction to Git and its usage. T o display the manual page for the version of Git included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man gittutorial' gittutorial-2(7) — T he manual page named gittutorial-2 provides the second part of a brief introduction to Git and its usage. T o display the manual page for the version of Git included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man gittutorial-2' Git User's Manual — HT ML documentation for Git is located at /opt/rh/devtoolset2/root/usr/share/doc/devtoolset-2-git-1.8.4 /user-m anual.htm l. Online Documentation Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides more information about Git and revision control systems in general. Pro Git — T he online version of the Pro Git book provides a detailed description of Git, its concepts and its usage. See Also Section A.4, “Changes in Git” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of Git. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more 55 Red Hat D eveloper Toolset 2.x User Guide information on how to install it on your system. 56 Part V. D ebugging Tools Part V. Debugging Tools 57 Red Hat D eveloper Toolset 2.x User Guide Chapter 8. GNU Debugger (GDB) T he GNU Debugger, commonly abbreviated as GDB, is a command line tool that can be used to debug programs written in various programming languages. It allows you to inspect memory within the code being debugged, control the execution state of the code, detect the execution of particular sections of code, and much more. Red Hat Developer T oolset is distributed with GDB 7.6.1. T his version is more recent than the version included in Red Hat Enterprise Linux and the previous release of Red Hat Developer T oolset, and provides numerous bug fixes and enhancements, including improved support for Python scripting, ambiguous line specifications, and tracepoints, as well as improved inferior control commands and handling of C++ debugee executables. For a detailed list of changes, see Section A.5, “Changes in GDB”. 8.1. Installing the GNU Debugger In Red Hat Developer T oolset, the GNU Debugger is provided by the devtoolset-2-gdb package and is automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of the GNU Debugger is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. On Red Hat Enterprise Linux 5, the GNU Debugger does not support build IDs and as a consequence, it is unable to determine the versions of binaries that created a particular core dump file. In addition, the GNU Debugger for Red Hat Enterprise Linux 5 does not advise users which RPM packages with debugging information to install. 8.2. Preparing a Program for Debugging Compiling Programs with Debugging Information T o compile a C program with debugging information that can be read by the GNU Debugger, make sure the gcc compiler is run with the -g option. T o do so on the command line, use a command in the following form: scl enable devtoolset-2 'gcc -g -o output_file input_file...' Similarly, to compile a C++ program with debugging information, run: scl enable devtoolset-2 'g++ -g -o output_file input_file...' 58 Chapter 8. GNU D ebugger (GD B) Example 8.1. Compiling a C Program With Debugging Information Consider a source file named fibonacci.c that has the following contents: #include <stdio.h> #include <limits.h> int main (int argc, unsigned long int unsigned long int unsigned long int char *argv[]) { a = 0; b = 1; sum; while (b < LONG_MAX) { printf("%ld ", b); sum = a + b; a = b; b = sum; } return 0; } T o compile this program on the command line using GCC from Red Hat Developer T oolset with debugging information for the GNU Debugger, type: ~]$ scl enable devtoolset-2 'gcc -g -o fibonacci fibonacci.c' T his creates a new binary file called fibonacci in the current working directory. Installing Debugging Information for Existing Packages T o install debugging information for a package that is already installed on the system, type the following at a shell prompt as root: debuginfo-install package_name Note that the yum-utils package must be installed for the debuginfo-install utility to be available on your system. Example 8.2. Installing Debugging Information for the glibc Package T o install debugging information for the glibc package, type: ~]# debuginfo-install glibc Loaded plugins: product-id, refresh-packagekit, subscription-manager --> Running transaction check ---> Package glibc-debuginfo.x86_64 0:2.12-1.47.el6_2.5 will be installed ... 8.3. Running the GNU Debugger 59 Red Hat D eveloper Toolset 2.x User Guide T o run the GNU Debugger on a program you want to debug, type the following at a shell prompt: scl enable devtoolset-2 'gdb file_name' T his starts the gdb debugger in interactive mode and displays the default prompt, (gdb). T o quit the debugging session and return to the shell prompt, run the following command at any time: quit Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset gdb as default: scl enable devtoolset-2 'bash' Note T o verify the version of gdb you are using at any point, type the following at a shell prompt: which gdb Red Hat Developer T oolset's gdb executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset gdb: gdb -v Example 8.3. Running the gdb Utility on the fibonacci Binary File Assuming that you have successfully compiled the fibonacci binary file as shown in Example 8.1, “Compiling a C Program With Debugging Information”, you can start debugging it with gdb by typing the following at a shell prompt: ~]$ scl enable devtoolset-2 'gdb fibonacci' GNU gdb (GDB) Red Hat Enterprise Linux (7.4.50.20120120-43.el6) Copyright (C) 2012 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-redhat-linux-gnu". For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. (gdb) 8.4. Listing Source Code T o view the source code of the program you are debugging, run the following command: 60 Chapter 8. GNU D ebugger (GD B) list Before you start the execution of the program you are debugging, gdb displays first ten lines of the source code and any subsequent use of this command lists another ten lines. Once you start the execution, gdb displays the lines that are surrounding the line on which the execution stops, typically when you set a breakpoint. You can also display the code that is surrounding a particular line. T o do so, run the command in the following form: list [file_name:]line_number Similarly, to display the code that is surrounding the beginning of a particular function, run: list [file_name:]function_name Note that you can change the number of lines the list command displays by running the following command: set listsize number Example 8.4 . Listing the Source Code of the fibonacci Binary File T he fibonacci.c file listed in Example 8.1, “Compiling a C Program With Debugging Information” has exactly 17 lines. Assuming that you have compiled it with debugging information and you want the gdb utility to be capable of listing the entire source code, you can run the following command to change the number of listed lines to 20: (gdb) set listsize 20 You can now display the entire source code of the file you are debugging by running the list command with no additional arguments: (gdb) list 1 #include <stdio.h> 2 #include <limits.h> 3 4 int main (int argc, char *argv[]) { 5 unsigned long int a = 0; 6 unsigned long int b = 1; 7 unsigned long int sum; 8 9 while (b < LONG_MAX) { 10 printf("%ld ", b); 11 sum = a + b; 12 a = b; 13 b = sum; 14 } 15 16 return 0; 17 } 61 Red Hat D eveloper Toolset 2.x User Guide 8.5. Setting Breakpoints Setting a New Breakpoint T o set a new breakpoint at a certain line, run the following command: break [file_name:]line_number You can also set a breakpoint on a certain function: break [file_name:]function_name Example 8.5. Setting a New Breakpoint Assuming that you have compiled the fibonacci.c file listed in Example 8.1, “Compiling a C Program With Debugging Information” with debugging information, you can set a new breakpoint at line 10 by running the following command: (gdb) break 10 Breakpoint 1 at 0x4004e5: file fibonacci.c, line 10. Listing Breakpoints T o display a list of currently set breakpoints, run the following command: info breakpoints Example 8.6. Listing Breakpoints Assuming that you have followed the instructions in Example 8.5, “Setting a New Breakpoint”, you can display the list of currently set breakpoints by running the following command: (gdb) info breakpoints Num Type Disp Enb Address What 1 breakpoint keep y 0x00000000004004e5 in main at fibonacci.c:10 Deleting Existing Breakpoints T o delete a breakpoint that is set at a certain line, run the following command: clear line_number Similarly, to delete a breakpoint that is set on a certain function, run: clear function_name You can also delete all breakpoints at once. T o do so, run the clear command with no additional arguments: 62 Chapter 8. GNU D ebugger (GD B) clear Example 8.7. Deleting an Existing Breakpoint Assuming that you have compiled the fibonacci.c file listed in Example 8.1, “Compiling a C Program With Debugging Information” with debugging information, you can set a new breakpoint at line 7 by running the following command: (gdb) break 7 Breakpoint 2 at 0x4004e3: file fibonacci.c, line 7. T o remove this breakpoint, type: (gdb) clear 7 Deleted breakpoint 2 8.6. Starting Execution T o start execution of the program you are debugging, run the following command: run If the program accepts any command line arguments, you can provide them as arguments to the run command: run argument… T he execution stops when a first breakpoint (if any) is reached, when an error occurs, or when the program terminates. Example 8.8. Executing the fibonacci Binary File Assuming that you have followed the instructions in Example 8.5, “Setting a New Breakpoint”, you can execute the fibonacci binary file by running the following command: (gdb) run Starting program: /home/john/fibonacci Breakpoint 1, main (argc=1, argv=0x7fffffffe4d8) at fibonacci.c:10 10 printf("%ld ", b); 8.7. Displaying Current Values T he gdb utility allows you to display the value of almost anything that is relevant to the program, from a variable of any complexity to a valid expression or even a library function. However, the most common task is to display the value of a variable. T o display the current value of a certain variable, run the following command: 63 Red Hat D eveloper Toolset 2.x User Guide print variable_name Example 8.9. Displaying the Current Values of Variables Assuming that you have followed the instructions in Example 8.8, “Executing the fibonacci Binary File” and the execution of the fibonacci binary stopped after reaching the breakpoint at line 10, you can display the current values of variables a and b as follows: (gdb) print a $1 = 0 (gdb) print b $2 = 1 8.8. Continuing Execution T o resume the execution of the program you are debugging after it reached a breakpoint, run the following command: continue T he execution stops again when another breakpoint is reached. T o skip a certain number of breakpoints (typically when you are debugging a loop), you can run the continue command in the following form: continue number T he gdb utility also allows you to stop the execution after executing a single line of code. T o do so, run: step Finally, you can execute a certain number of lines by using the step command in the following form: step number 64 Chapter 8. GNU D ebugger (GD B) Example 8.10. Continuing the Execution of the fibonacci Binary File Assuming that you have followed the instructions in Example 8.8, “Executing the fibonacci Binary File” and the execution of the fibonacci binary stopped after reaching the breakpoint at line 10, you can resume the execution by running the following command: (gdb) continue Continuing. Breakpoint 1, main (argc=1, argv=0x7fffffffe4d8) at fibonacci.c:10 10 printf("%ld ", b); T he execution stops the next time the breakpoint is reached. T o execute next three lines of code, type: (gdb) step 3 13 b = sum; T his allows you to verify the current value of the sum variable before it is assigned to b: (gdb) print sum $3 = 2 8.9. Additional Resources A detailed description of the GNU Debugger and all its features is beyond the scope of this book. For more information, see the resources listed below. Online Documentation Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides more information on the GNU Debugger and debugging. GDB Documentation — T he official GDB documentation includes the GDB User Manual and other reference material. See Also Section A.5, “Changes in GDB” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of the GNU Debugger and the version distributed in the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 2, Eclipse provides a general introduction to the Eclipse development environment, and describes how to use it with the tools from Red Hat Developer T oolset. Chapter 3, GNU Compiler Collection (GCC) provides further information on how to compile programs written in C, C++, and Fortran. Chapter 9, strace documents how to use the strace utility to monitor system calls that a program uses and signals it receives. Chapter 10, memstomp documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards. 65 Red Hat D eveloper Toolset 2.x User Guide 66 Chapter 9. strace Chapter 9. strace strace is a diagnostic and debugging tool for the command line that can be used to trace system calls that are made and received by a running process. It records the name of each system call, its arguments, and its return value, as well as signals received by the process and other interactions with the kernel, and prints this record to standard error output or a selected file. Red Hat Developer T oolset is distributed with strace 4 .7. 9.1. Installing strace In Red Hat Enterprise Linux, the strace utility is provided by the devtoolset-2-strace package and is automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of strace is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. 9.2. Using strace T o run the strace utility on a program you want to analyze, type the following at a shell prompt: scl enable devtoolset-2 'strace program [argument...]' Replace program with the name of the program you want to analyze, and argument with any command line options and arguments you want to supply to this program. Alternatively, you can run the utility on an already running process by using the -p command line option followed by the process ID: scl enable devtoolset-2 'strace -p process_id' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset strace as default: scl enable devtoolset-2 'bash' 67 Red Hat D eveloper Toolset 2.x User Guide Note T o verify the version of strace you are using at any point, type the following at a shell prompt: which strace Red Hat Developer T oolset's strace executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset strace: strace -V 9.2.1. Redirecting Output to a File By default, strace prints the name of each system call, its arguments and the return value to standard error output. T o redirect this output to a file, use the -o command line option followed by the file name: scl enable devtoolset-2 'strace -o file_name program [argument...]' Replace file_name with the name of the file. Example 9.1. Redirecting Output to a File Consider a slightly modified version of the fibonacci file from Example 8.1, “Compiling a C Program With Debugging Information”. T his executable file displays the Fibonacci sequence and optionally allows you to specify how many members of this sequence to list. T o run the strace utility on this file and redirect the trace output to fibonacci.log, type: ~]$ scl enable devtoolset-2 'strace -o fibonacci.log ./fibonacci 20' 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181 6765 T his creates a new plain-text file called fibonacci.log in the current working directory. 9.2.2. Tracing Selected System Calls T o trace only a selected set of system calls, run the strace utility with the -e command line option: scl enable devtoolset-2 'strace -e expression program [argument...]' Replace expression with a comma-separated list of system calls to trace or any of the keywords listed in T able 9.1, “Commonly Used Values of the -e Option”. For a detailed description of all available values, see the strace(1) manual page. 68 Chapter 9. strace T able 9.1. Commonly Used Values of the -e Option Value Description file System calls that accept a file name as an argument. process System calls that are related to process management. network System calls that are related to networking. signal System calls that are related to signal management. ipc System calls that are related to inter-process communication (IPC). desc System calls that are related to file descriptors. Example 9.2. T racing Selected System Calls Consider the em ployee file from Example 10.1, “Using memstomp”. T o run the strace utility on this executable file and trace only the m m ap and m unm ap system calls, type: ~]$ scl enable devtoolset-2 'strace -e mmap,munmap ./employee' mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f896c744000 mmap(NULL, 61239, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f896c735000 mmap(0x3146a00000, 3745960, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x3146a00000 mmap(0x3146d89000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x189000) = 0x3146d89000 mmap(0x3146d8e000, 18600, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x3146d8e000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f896c734000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f896c733000 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f896c732000 munmap(0x7f896c735000, 61239) = 0 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f896c743000 John,[email protected], +++ exited with 0 +++ 9.2.3. Displaying Time Stamps T o prefix each line of the trace with the exact time of the day in hours, minutes, and seconds, run the strace utility with the -t command line option: scl enable devtoolset-2 'strace -t program [argument...]' T o also display milliseconds, supply the -t option twice: scl enable devtoolset-2 'strace -tt program [argument...]' T o prefix each line of the trace with the time required to execute the respective system call, use the -r command line option: 69 Red Hat D eveloper Toolset 2.x User Guide scl enable devtoolset-2 'strace -r program [argument...]' Example 9.3. Displaying T ime Stamps Consider an executable file named pwd. T o run the strace utility on this file and include time stamps in the output, type: ~]$ scl enable devtoolset-2 'strace -tt ./pwd' 19:43:28.011815 execve("./pwd", ["./pwd"], [/* 36 vars */]) = 0 19:43:28.012128 brk(0) = 0xcd3000 19:43:28.012174 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fc869cb0000 19:43:28.012427 open("/etc/ld.so.cache", O_RDONLY) = 3 19:43:28.012446 fstat(3, {st_mode=S_IFREG|0644, st_size=61239, ...}) = 0 19:43:28.012464 mmap(NULL, 61239, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fc869ca1000 19:43:28.012483 close(3) = 0 ... 19:43:28.013410 +++ exited with 0 +++ 9.2.4. Displaying a Summary T o display a summary of how much time was required to execute each system call, how many times were these system calls executed, and how many errors were encountered during their execution, run the strace utility with the -c command line option: scl enable devtoolset-2 'strace -c program [argument...]' Example 9.4 . Displaying a Summary Consider an executable file named lsblk. T o run the strace utility on this file and display a trace summary, type: ~]$ scl enable devtoolset-2 'strace -c ./lsblk > /dev/null' % time seconds usecs/call calls errors syscall ------ ----------- ----------- --------- --------- ---------------80.88 0.000055 1 106 16 open 19.12 0.000013 0 140 munmap 0.00 0.000000 0 148 read 0.00 0.000000 0 1 write 0.00 0.000000 0 258 close 0.00 0.000000 0 37 2 stat ... ------ ----------- ----------- --------- --------- ---------------100.00 0.000068 1790 35 total 9.3. Additional Resources A detailed description of strace and its features is beyond the scope of this book. For more information, see the resources listed below. 70 Chapter 9. strace Installed Documentation strace(1) — T he manual page for the strace utility provides detailed information about its usage. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man strace' See Also Section B.7, “Changes in strace” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of strace. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 8, GNU Debugger (GDB) provides information on how to debug programs written in C, C++, and Fortran. Chapter 10, memstomp documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards. 71 Red Hat D eveloper Toolset 2.x User Guide Chapter 10. memstomp memstomp is a command line tool that can be used to identify function calls with overlapping memory regions in situations when such an overlap is not permitted by various standards. It intercepts calls to the library functions listed in T able 10.1, “Function Calls Inspected by memstomp” and for each memory overlap, it displays a detailed backtrace to help you debug the problem. Similarly to Valgrind, the m em stom p utility inspects applications without the need to recompile them. However, it is much faster than this tool and therefore serves as a convenient alternative to it. Red Hat Developer T oolset is distributed with memstomp 0.1.4 . 72 Chapter 10. memstomp T able 10.1. Function Calls Inspected by memstomp Function Description m em cpy Copies n bytes from one memory area to another and returns a pointer to the second memory area. m em ccpy Copies a maximum of n bytes from one memory area to another and stops when a certain character is found. It either returns a pointer to the byte following the last written byte, or NULL if the given character is not found. m em pcpy Copies n bytes from one memory area to another and returns a pointer to the byte following the last written byte. strcpy Copies a string from one memory area to another and returns a pointer to the second string. stpcpy Copies a string from one memory area to another and returns a pointer to the terminating null byte of the second string. strncpy Copies a maximum of n characters from one string to another and returns a pointer to the second string. stpncpy Copies a maximum of n characters from one string to another. It either returns a pointer to the terminating null byte of the second string, or if the string is not null-terminated, a pointer to the byte following the last written byte. strcat Appends one string to another while overwriting the terminating null byte of the second string and adding a new one at its end. It returns a pointer to the new string. strncat Appends a maximum of n characters from one string to another while overwriting the terminating null byte of the second string and adding a new one at its end. It returns a pointer to the new string. wm em cpy T he wide-character equivalent of the m em cpy() function that copies n wide characters from one array to another and returns a pointer to the second array. wm em pcpy T he wide-character equivalent of the m em pcpy() function that copies n wide characters from one array to another and returns a pointer to the byte following the last written wide character. wcscpy T he wide-character equivalent of the strcpy() function that copies a widecharacter string from one array to another and returns a pointer to the second array. wcsncpy T he wide-character equivalent of the strncpy() function that copies a maximum of n wide characters from one array to another and returns a pointer to the second string. wcscat T he wide-character equivalent of the strcat() function that appends one wide-character string to another while overwriting the terminating null byte of the second string and adding a new one at its end. It returns a pointer to the new string. wcsncat T he wide-character equivalent of the strncat() function that appends a maximum of n wide characters from one array to another while overwriting the terminating null byte of the second wide-character string and adding a new one at its end. It returns a pointer to the new string. 73 Red Hat D eveloper Toolset 2.x User Guide 10.1. Installing memstomp In Red Hat Developer T oolset, the m em stom p utility is provided by the devtoolset-2-memstomp package and is automatically installed with devtoolset-2-toolchain as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of memstomp is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. 10.2. Using memstomp T o run the m em stom p utility on a program you want to analyze, type the following at a shell prompt: scl enable devtoolset-2 'memstomp program [argument...]' T o immediately terminate the analyzed program when a problem is detected, run the utility with the -kill (or -k for short) command line option: scl enable devtoolset-2 'memstomp --kill program [argument...]' T he use of the --kill option is especially recommended if you are analyzing a multi-threaded program; the internal implementation of backtraces is not thread-safe and running the m em stom p utility on a multithreaded program without this command line option can therefore produce unreliable results. Additionally, if you have compiled the analyzed program with the debugging information or this debugging information is available to you, you can use the --debug-info (or -d) command line option to produce a more detailed backtrace: scl enable devtoolset-2 'memstomp --debug-info program [argument...]' For detailed instructions on how to compile your program with the debugging information built in the binary file, see Section 8.2, “Preparing a Program for Debugging”. For information on how to install debugging information for any of the Red Hat Developer T oolset packages, see Section 1.5.4, “Installing Debugging Information”. Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset m em stom p as default: scl enable devtoolset-2 'bash' 74 Chapter 10. memstomp Example 10.1. Using memstomp In the current working directory, create a source file named em ployee.c with the following contents: #include <stdio.h> #include <string.h> #define BUFSIZE 80 int main(int argc, char *argv[]) { char employee[BUFSIZE] = "John,Doe,[email protected]"; char name[BUFSIZE] = {0}; char surname[BUFSIZE] = {0}; char *email; size_t length; /* Extract the information: */ memccpy(name, employee, ',', BUFSIZE); length = strlen(name); memccpy(surname, employee + length, ',', BUFSIZE); length += strlen(surname); email = employee + length; /* Compose the new entry: */ strcat(employee, surname); strcpy(employee, name); strcat(employee, email); /* Print the result: */ puts(employee); return 0; } Compile this program into a binary file named em ployee by using the following command: ~]$ scl enable devtoolset-2 'gcc -rdynamic -g -o employee employee.c' T o identify erroneous function calls with overlapping memory regions, type: ~]$ scl enable devtoolset-2 'memstomp --debug-info ./employee' memstomp: 0.1.4 successfully initialized for process employee (pid 14887). strcat(dest=0x7fff13afc265, src=0x7fff13afc269, bytes=21) overlap for employee(14887) ??:0 strcpy() ??:0 strcpy() ??:0 _Exit() ??:0 strcat() employee.c:26 main() ??:0 __libc_start_main() ??:0 _start() John,[email protected], 75 Red Hat D eveloper Toolset 2.x User Guide 10.3. Additional Resources A detailed description of m em stom p and its features is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation m em stom p(1) — T he manual page for the m em stom p utility provides detailed information about its usage. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man memstomp' See Also Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 8, GNU Debugger (GDB) provides information on how to debug programs written in C, C++, and Fortran. Chapter 9, strace documents how to use the strace utility to monitor system calls that a program uses and signals it receives. Chapter 12, Valgrind explains how to use valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls. 76 Part VI. Performance Monitoring Tools Part VI. Performance Monitoring Tools 77 Red Hat D eveloper Toolset 2.x User Guide Chapter 11. SystemTap SystemT ap is a tracing and probing tool that allows users to monitor the activities of the entire system without needing to instrument, recompile, install, and reboot. It is programmable with a custom scripting language, which gives it expressiveness (to trace, filter, and analyze) and reach (to look into the running kernel and applications). SystemT ap can monitor various types of events, such as function calls within the kernel or applications, timers, tracepoints, performance counters, and so on. Some included example scripts produce output similar to netstat, ps, top, and iostat, others include pretty-printed function callgraph traces or tools for working around security bugs. Red Hat Developer T oolset is distributed with SystemT ap 2.1. T able 11.1. T ools Distributed with SystemT ap for Red Hat Developer T oolset Name Description stap T ranslates probing instructions into C code, builds a kernel module, and loads it into a running Linux kernel. staprun Loads, unloads, attaches to, and detaches from kernel modules built with the stap utility. stapsh Serves as a remote shell for SystemT ap. stap-prep Determines and—if possible—downloads the kernel information packages that are required to run SystemT ap. stap-m erge Merges per-CPU files. T his script is automatically executed when the stap utility is executed with the -b command line option. stap-report Gathers important information about the system for the purpose of reporting a bug in SystemT ap. 11.1. Installing SystemTap In Red Hat Developer T oolset, System T ap is provided by the devtoolset-2-systemtap package and is automatically installed with devtoolset-2-perftools as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of SystemT ap is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. In order to place instrumentation into the Linux kernel, SystemT ap may also require installation of additional packages with debugging information. T o determine which packages to install, run the stapprep utility as follows: scl enable devtoolset-2 'stap-prep' Note that if you execute this command as the root user, the utility automatically offers the packages for installation. For more information on how to install these packages on your system, see the Red Hat Enterprise Linux SystemTap Beginners Guide. 78 Chapter 11. SystemTap 11.2. Using SystemTap T o execute any of the tools that are part of SystemT ap, type the following at a shell prompt: scl enable devtoolset-2 'tool [option...]' See T able 11.1, “T ools Distributed with SystemT ap for Red Hat Developer T oolset” for a list of tools that are distributed with SystemT ap. For example, to run the stap tool to build an instrumentation module, type: scl enable devtoolset-2 'stap [option...] argument...' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset SystemT ap as default: scl enable devtoolset-2 'bash' Note T o verify the version of SystemT ap you are using at any point, type the following at a shell prompt: which stap Red Hat Developer T oolset's stap executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset SystemT ap: stap -V 11.3. Additional Resources A detailed description of SystemT ap and its features is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation stap(1) — T he manual page for the stap command provides detailed information on its usage, as well as references to other related manual pages. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man stap' staprun(8) — T he manual page for the staprun command provides detailed information on its usage. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man staprun' 79 Red Hat D eveloper Toolset 2.x User Guide SystemTap Tapset Reference Manual — HT ML documentation on the most common tapset definitions is located at /opt/rh/devtoolset-2/root/usr/share/doc/devtoolset-2system tap-client-2.1/index.htm l. Online Documentation Red Hat Enterprise Linux 6 SystemT ap Beginners Guide — T he SystemTap Beginners Guide for Red Hat Enterprise Linux 6 provides an introduction to SystemT ap and its usage. Red Hat Enterprise Linux 5 SystemT ap Beginners Guide — T he SystemTap Beginners Guide for Red Hat Enterprise Linux 5 provides an introduction to SystemT ap and its usage. Red Hat Enterprise Linux 6 SystemT ap T apset Reference — T he SystemTap Tapset Reference for Red Hat Enterprise Linux 6 provides further details about SystemT ap. Red Hat Enterprise Linux 5 SystemT ap T apset Reference — T he SystemTap Tapset Reference for Red Hat Enterprise Linux 5 provides further details about SystemT ap. T he SystemT ap Documentation — T he official SystemT ap documentation provides further documentation on SystemT ap, as well as numerous examples of SystemT ap scripts. See Also Section B.8, “Changes in SystemT ap” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of SystemT ap and the version distributed in the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 12, Valgrind explains how to use Valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls. Chapter 13, OProfile explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why. Chapter 14, Dyninst documents how to use the Dyninst library to instrument a user-space executable. 80 Chapter 12. Valgrind Chapter 12. Valgrind Valgrind is an instrumentation framework that ships with a number of tools to profile applications. It can be used to detect various memory errors and memory management problems, such as the use of uninitialized memory or improper allocation and freeing of memory, or to identify the use of improper arguments in system calls. For a complete list of profiling tools that are distributed with the Red Hat Developer T oolset version of Valgrind, see T able 12.1, “T ools Distributed with Valgrind for Red Hat Developer T oolset”. Valgrind profiles an application by rewriting it and instrumenting the rewritten binary. T his allows you to profile your application without the need to recompile it, but it also makes Valgrind significantly slower than other profilers, especially when performing extremely detailed runs. It is therefore not suited to debugging time-specific issues, or kernel-space debugging. Red Hat Developer T oolset is distributed with Valgrind 3.8.1. T his version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements. T able 12.1. T ools Distributed with Valgrind for Red Hat Developer T oolset Name Description Memcheck Detects memory management problems by intercepting system calls and checking all read and write operations. Cachegrind Identifies the sources of cache misses by simulating the level 1 instruction cache (I1), level 1 data cache (D1), and unified level 2 cache (L2). Callgrind Generates a call graph representing the function call history. Helgrind Detects synchronization errors in multithreaded C, C++, and Fortran programs that use POSIX threading primitives. DRD Detects errors in multithreaded C and C++ programs that use POSIX threading primitives or any other threading concepts that are built on top of these POSIX threading primitives. Massif Monitors heap and stack usage. 12.1. Installing Valgrind In Red Hat Developer T oolset, Valgrind is provided by the devtoolset-2-valgrind package and is automatically installed with devtoolset-2-perftools. If you intend to use Valgrind to profile parallel programs that use the Message Passing Interface (MPI) protocol, also install the devtoolset-2-valgrindopenmpi package by typing the following at a shell prompt as root: yum install devtoolset-2-valgrind-openmpi For detailed instructions on how to install Red Hat Developer T oolset and related packages to your system, see Section 1.5, “Installing Red Hat Developer T oolset”. 81 Red Hat D eveloper Toolset 2.x User Guide Note T he Red Hat Developer T oolset version of Valgrind is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. Note that if you use Valgrind in combination with the GNU Debugger, it is recommended that you use the version of GDB that is included in Red Hat Developer T oolset to ensure that all features are fully supported. 12.2. Using Valgrind T o run any of the Valgrind tools on a program you want to profile, type the following at a shell prompt: scl enable devtoolset-2 'valgrind [--tool=tool] program [argument...]' See T able 12.1, “T ools Distributed with Valgrind for Red Hat Developer T oolset” for a list of tools that are distributed with Valgrind. T he argument of the --tool command line option must be specified in lower case, and if this option is omitted, Valgrind uses Memcheck by default. For example, to run Cachegrind on a program to identify the sources of cache misses, type: scl enable devtoolset-2 'valgrind --tool=cachegrind program [argument...]' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset Valgrind as default: scl enable devtoolset-2 'bash' Note T o verify the version of Valgrind you are using at any point, type the following at a shell prompt: which valgrind Red Hat Developer T oolset's valgrind executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset Valgrind: valgrind --version 12.3. Additional Resources A detailed description of Valgrind and its features is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation valgrind(1) — T he manual page for the valgrind utility provides detailed information on how to 82 Chapter 12. Valgrind use Valgrind. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man valgrind' Valgrind Documentation — HT ML documentation for Valgrind is located at /opt/rh/devtoolset2/root/usr/share/doc/devtoolset-2-valgrind-3.8.1/htm l/index.htm l. Online Documentation Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides more information about Valgrind and its Eclipse plug-in. Red Hat Enterprise Linux 6 Performance T uning Guide — T he Performance Tuning Guide for Red Hat Enterprise Linux 6 provides more detailed information about using Valgrind to profile applications. See Also Section A.6, “Changes in Valgrind” provides a comprehensive list of features and improvements over the Red Hat Enterprise Linux system version of Valgrind and the version distributed in the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 10, memstomp documents how to use the memstomp utility to identify calls to library functions with overlapping memory regions that are not allowed by various standards. Chapter 11, SystemTap provides an introduction to SystemT ap and explains how to use it to monitor the activities of a running system. Chapter 13, OProfile explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why. Chapter 14, Dyninst documents how to use the Dyninst library to instrument a user-space executable. 83 Red Hat D eveloper Toolset 2.x User Guide Chapter 13. OProfile OProfile is a low overhead, system-wide profiler that uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system, such as when memory is referenced, the number of level 2 cache (L2) requests, and the number of hardware interrupts received. It consists of a configuration utility, a daemon for collecting data, and a number of tools that can be used to transform the data into a human-readable form. For a complete list of tools that are distributed with the Red Hat Developer T oolset version of OProfile, see T able 13.1, “T ools Distributed with OProfile for Red Hat Developer T oolset”. OProfile profiles an application without adding any instrumentation by recording the details of every nth event. T his allows it to consume fewer resources than Valgrind, but also causes its samples to be less precise. Unlike Valgrind, which only collects data for a single process and its children in user-space, OProfile is well suited to collect system-wide data on both user-space and kernel-space processes, and requires root privileges to run. Red Hat Developer T oolset is distributed with OProfile 0.9.8. T his version is more recent than the version included in Red Hat Enterprise Linux and provides numerous bug fixes and enhancements. T able 13.1. T ools Distributed with OProfile for Red Hat Developer T oolset Name Description oprofiled T he OProfile daemon that collects profiling data. opcontrol Starts, stops, and configures the OProfile daemon. opannotate Generates an annotated source file or assembly listing from the profiling data. oparchive Generates a directory containing executable, debug, and sample files. opgprof Generates a summary of a profiling session in a format compatible with gprof. ophelp Displays a list of available events. opim port Converts a sample database file from a foreign binary format to the native format. opjitconv Converts a just-in-time (JIT ) dump file to the Executable and Linkable Format (ELF). opreport Generates image and symbol summaries of a profiling session. 13.1. Installing OProfile In Red Hat Developer T oolset, OProfile is provided by the devtoolset-2-oprofile package and is automatically installed with devtoolset-2-perftools as described in Section 1.5, “Installing Red Hat Developer T oolset”. Note T he Red Hat Developer T oolset version of OProfile is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. Note that the operf utility relies on a kernel feature that is currently not available in Red Hat Enterprise Linux 5, and as a consequence, this utility only works and is supported on Red Hat Enterprise Linux 6. 84 Chapter 13. OProfile 13.2. Using OProfile T o run any of the tools that are distributed with OProfile, type the following at a shell prompt as root: scl enable devtoolset-2 'tool [option...]' See T able 13.1, “T ools Distributed with OProfile for Red Hat Developer T oolset” for a list of tools that are distributed with OProfile. For example, to use the ophelp command to list available events in the XML format, type: scl enable devtoolset-2 'ophelp -X' Note that you can execute any command using the scl utility, causing it to be run with the Red Hat Developer T oolset binaries used in preference to the Red Hat Enterprise Linux system equivalent. T his allows you to run a shell session with Red Hat Developer T oolset OProfile as default: scl enable devtoolset-2 'bash' Note T o verify the version of OProfile you are using at any point, type the following at a shell prompt: which opcontrol Red Hat Developer T oolset's opcontrol executable path will begin with /opt. Alternatively, you can use the following command to confirm that the version number matches that for Red Hat Developer T oolset OProfile: opcontrol --version 13.3. Additional Resources A detailed description of OProfile and its features is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation oprofile(1) — T he manual page named oprofile provides an overview of OProfile and available tools. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man oprofile' opannotate(1), oparchive(1), opcontrol(1), opgprof(1), ophelp(1), opimport(1), opreport(1) — Manual pages for various tools distributed with OProfile provide more information on their respective usage. T o display the manual page for the version included in Red Hat Developer T oolset, type: scl enable devtoolset-2 'man tool' 85 Red Hat D eveloper Toolset 2.x User Guide Online Documentation Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides more information on OProfile. Red Hat Enterprise Linux 6 Deployment Guide — T he Deployment Guide for Red Hat Enterprise Linux 6 describes in detail how to install, configure, and start using OProfile on this system. Red Hat Enterprise Linux 5 Deployment Guide — T he Deployment Guide for Red Hat Enterprise Linux 5 describes in detail how to install, configure, and start using OProfile on this system. See Also Section A.7, “Changes in OProfile” provides a comprehensive list of changes and improvements over the Red Hat Enterprise Linux system version of OProfile and the version distributed in the previous release of Red Hat Developer T oolset. Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 11, SystemTap provides an introduction to SystemT ap and explains how to use it to monitor the activities of a running system. Chapter 12, Valgrind explains how to use Valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls. Chapter 14, Dyninst documents how to use the Dyninst library to instrument a user-space executable. 86 Chapter 14. D yninst Chapter 14. Dyninst T he Dyninst library provides an application programming interface (API) for instrumenting and working with user-space executables during their execution. It can be used to insert code into a running program, change certain subroutine calls, or even remove them from the program, and serves as a valuable debugging and performance monitoring tool. T he Dyninst API is also commonly used along with SystemT ap to allow non-root users to instrument user-space executables. Red Hat Developer T oolset is distributed with Dyninst 8.0. 14.1. Installing Dyninst In Red Hat Developer T oolset, the Dyninst library is provided by the devtoolset-2-dyninst package and is automatically installed with devtoolset-2-perftools as described in Section 1.5, “Installing Red Hat Developer T oolset”. In addition, it is recommended that you also install the GNU Compiler Collection provided by the devtoolset-2-toolchain package. Note T he Red Hat Developer T oolset version of Dyninst is available for both Red Hat Enterprise Linux 5 and Red Hat Enterprise Linux 6 on 32-bit and 64-bit Intel and AMD architectures. If you intend to write a custom instrumentation for binaries, install the relevant header files by running the following command as root: yum install devtoolset-2-dyninst-devel You can also install API documentation for this library by typing the following at a shell prompt as root: yum install devtoolset-2-dyninst-doc For a complete list of documents that are included in the devtoolset-2-dyninst-doc package, see Section 14.3, “Additional Resources”. For detailed instructions on how to install optional packages to your system, see Section 1.5, “Installing Red Hat Developer T oolset”. 14.2. Using Dyninst 14.2.1. Using Dyninst with SystemTap T o use Dyninst along with SystemT ap to allow non-root users to instrument user-space executables, run the stap command with the --dyninst (or --runtim e=dyninst) command line option. T his tells stap to translate a SystemT ap script into C code that uses the Dyninst library, compile this C code into a shared library, and then load the shared library and run the script. Note that when executed like this, the stap command also requires the -c or -x command line option to be specified. T o use the Dyninst runtime to instrument an executable file, type the following at a shell prompt: scl enable devtoolset-2 "stap --dyninst -c 'command' [option...] [argument...]" Similarly, to use the Dyninst runtime to instrument a user's process, type: 87 Red Hat D eveloper Toolset 2.x User Guide scl enable devtoolset-2 "stap --dyninst -x process_id [option...] [argument...]" See Chapter 11, SystemTap for more information about the Red Hat Developer T oolset version of SystemT ap. For a general introduction to SystemT ap and its usage, see the SystemTap Beginners Guide for Red Hat Enterprise Linux. 88 Chapter 14. D yninst Example 14 .1. Using Dyninst with SystemT ap Consider a source file named exercise.C that has the following contents: #include <stdio.h> void print_iteration(int value) { printf("Iteration number %d\n", value); } int main(int argc, char **argv) { int i; printf("Enter the starting number: "); scanf("%d", &i); for(; i>0; --i) print_iteration(i); return 0; } T his program prompts the user to enter a starting number and then counts down to 1, calling the print_iteration() function for each iteration in order to print the number to standard output. T o compile this program on the command line using the g++ compiler from Red Hat Developer T oolset, type the following at a shell prompt: ~]$ scl enable devtoolset-2 'g++ -g -o exercise exercise.C' Now consider another source file named count.stp with the following contents: #!/usr/bin/stap global count = 0 probe process.function("print_iteration") { count++ } probe end { printf("Function executed %d times.\n", count) } T his SystemT ap script prints the total number of times the print_iteration() function was called during the execution of a process. T o run this script on the exercise binary file, type: ~]$ scl enable devtoolset-2 "stap --dyninst -c './exercise' count.stp" Enter the starting number: 5 Iteration number 5 Iteration number 4 Iteration number 3 Iteration number 2 Iteration number 1 Function executed 5 times. 14.2.2. Using Dyninst as a Stand-alone Application 89 Red Hat D eveloper Toolset 2.x User Guide Before using the Dyninst library as a stand-alone application, set the value of the DYNINST API_RT _LIB environment variable to the path to the runtime library file. If you are running a 64-bit system, you can do so by typing the following at a shell prompt: export DYNINSTAPI_RT_LIB=/opt/rh/devtoolset2/root/usr/lib64/dyninst/libdyninstAPI_RT.so.8.0 If you are running a 32-bit system, type: export DYNINSTAPI_RT_LIB=/opt/rh/devtoolset2/root/usr/lib/dyninst/libdyninstAPI_RT.so.8.0 T his sets the DYNINST API_RT _LIB environment variable in the current shell session. Example 14.2, “Using Dyninst as a Stand-alone Application” illustrates how to write and build a program to monitor the execution of a user-space process. For a detailed explanation of how to use Dyninst, see the resources listed in Section 14.3, “Additional Resources”. 90 Chapter 14. D yninst Example 14 .2. Using Dyninst as a Stand-alone Application Consider the exercise.C source file from Example 14.1, “Using Dyninst with SystemT ap”: this program prompts the user to enter a starting number and then counts down to 1, calling the print_iteration() function for each iteration in order to print the number to standard output. Now consider another source file named count.C with the following contents: 91 Red Hat D eveloper Toolset 2.x User Guide #include #include #include #include #include #include #include #include <stdio.h> <fcntl.h> "BPatch.h" "BPatch_process.h" "BPatch_function.h" "BPatch_Vector.h" "BPatch_thread.h" "BPatch_point.h" void usage() { fprintf(stderr, "Usage: count <process_id> <function>\n"); } // Global information for counter BPatch_variableExpr *counter = NULL; void createCounter(BPatch_process *app, BPatch_image *appImage) { int zero = 0; counter = app->malloc(*appImage->findType("int")); counter->writeValue(&zero); } bool interceptfunc(BPatch_process *app, BPatch_image *appImage, char *funcName) { BPatch_Vector<BPatch_function *> func; appImage->findFunction(funcName, func); if(func.size() == 0) { fprintf(stderr, "Unable to find function to instrument()\n"); exit (-1); } BPatch_Vector<BPatch_snippet *> incCount; BPatch_Vector<BPatch_point *> *points; points = func[0]->findPoint(BPatch_entry); if ((*points).size() == 0) { exit (-1); } BPatch_arithExpr counterPlusOne(BPatch_plus, *counter, BPatch_constExpr(1)); BPatch_arithExpr addCounter(BPatch_assign, *counter, counterPlusOne); return app->insertSnippet(addCounter, *points); } void printCount(BPatch_thread *thread, BPatch_exitType) { int val = 0; counter->readValue(&val, sizeof(int)); fprintf(stderr, "Function executed %d times.\n", val); } BPatch bpatch; int main(int argc, char *argv[]) { int pid; if (argc != 3) { usage(); exit(1); } pid = atoi(argv[1]); 92 Chapter 14. D yninst BPatch_process *app = bpatch.processAttach(NULL, pid); if (!app) exit (-1); BPatch_image *appImage = app->getImage(); createCounter(app, appImage); fprintf(stderr, "Finding function %s(): ", argv[2]); BPatch_Vector<BPatch_function*> countFuncs; fprintf(stderr, "OK\nInstrumenting function %s(): ", argv[2]); interceptfunc(app, appImage, argv[2]); bpatch.registerExitCallback(printCount); fprintf(stderr, "OK\nWaiting for process %d to exit...\n", pid); app->continueExecution(); while (!app->isTerminated()) bpatch.waitForStatusChange(); return 0; } T his program accepts a process ID and a function name as command line arguments and then prints the total number of times the function was called during the execution of the process. You can use the following Makefile to build these two files: DTS = /opt/rh/devtoolset-2/root CXXFLAGS = -g -I$(DTS)/usr/include/dyninst LBITS := $(shell getconf LONG_BIT) ifeq ($(LBITS),64) DYNINSTLIBS = $(DTS)/usr/lib64/dyninst else DYNINSTLIBS = $(DTS)/usr/lib/dyninst endif .PHONY: all all: count exercise count: count.C g++ $(CXXFLAGS) count.C -I /usr/include/dyninst -c g++ $(CXXFLAGS) count.o -L $(DYNINSTLIBS) -ldyninstAPI -o count exercise: exercise.C g++ $(CXXFLAGS) exercise.C -o exercise .PHONY: clean clean: rm -rf *~ *.o count exercise T o compile the two programs on the command line using the g++ compiler from Red Hat Developer T oolset, run the m ake utility as follows: ~]$ scl enable devtoolset-2 make g++ -g -I/opt/rh/devtoolset-2/root/usr/include/dyninst count.C -c g++ -g -I/opt/rh/devtoolset-2/root/usr/include/dyninst count.o -L /opt/rh/devtoolset-2/root/usr/lib64/dyninst -ldyninstAPI -o count g++ -g -I/opt/rh/devtoolset-2/root/usr/include/dyninst exercise.C -o exercise T his creates new binary files called exercise and count in the current working directory. In one shell session, execute the exercise binary file as follows and wait for it to prompt you to enter the starting number: 93 Red Hat D eveloper Toolset 2.x User Guide ~]$ ./exercise Enter the starting number: Do not enter this number. Instead, start another shell session and type the following at its prompt to set the DYNINST API_RT _LIB environment variable and execute the count binary file: ~]$ export DYNINSTAPI_RT_LIB=/opt/rh/devtoolset2/root/usr/lib64/dyninst/libdyninstAPI_RT.so.8.0 ~]$ ./count `pidof exercise` print_iteration Finding function print_iteration(): OK Instrumenting function print_iteration(): OK Waiting for process 8607 to exit... Now switch back to the first shell session and enter the starting number as requested by the exercise program. For example: Enter the Iteration Iteration Iteration Iteration Iteration starting number: 5 number 5 number 4 number 3 number 2 number 1 When the exercise program terminates, the count program displays the number of times the print_iteration() function was executed: Function executed 5 times. 14.3. Additional Resources A detailed description of Dyninst and its features is beyond the scope of this book. For more information, see the resources listed below. Installed Documentation T he devtoolset-2-dyninst-doc package installs the following documents in the /opt/rh/devtoolset2/root/usr/share/doc/devtoolset-2-dyninst-doc-8.0/ directory: Dyninst Programmer's Guide — A detailed description of the Dyninst API is stored in the DyninstAPI.pdf file. DynC API Programmer's Guide — An introduction to DynC API is stored in the dynC_API.pdf file. ParseAPI Programmer's Guide — An introduction to the ParseAPI is stored in the ParseAPI.pdf file. PatchAPI Programmer's Guide — An introduction to PatchAPI is stored in the PatchAPI.pdf file. ProcControlAPI Programmer's Guide — A detailed description of ProcControlAPI is stored in the ProcControlAPI.pdf file. StackwalkerAPI Programmer's Guide — A detailed description of StackwalkerAPI is stored in the stackwalker.pdf file. SymtabAPI Programmer's Guide — An introduction to SymtabAPI is stored in the Sym tabAPI.pdf file. 94 Chapter 14. D yninst InstructionAPI Reference Manual — A detailed description of the InstructionAPI is stored in the InstructionAPI.pdf file. For information on how to install this package on your system, see Section 14.1, “Installing Dyninst”. Online Documentation Dyninst Home Page — T he project home page provides links to additional documentation and related publications. Red Hat Enterprise Linux 6 SystemT ap Beginners Guide — T he SystemTap Beginners Guide for Red Hat Enterprise Linux 6 provides an introduction to SystemT ap and its usage. Red Hat Enterprise Linux 5 SystemT ap Beginners Guide — T he SystemTap Beginners Guide for Red Hat Enterprise Linux 5 provides an introduction to SystemT ap and its usage. Red Hat Enterprise Linux 6 SystemT ap T apset Reference — T he SystemTap Tapset Reference for Red Hat Enterprise Linux 6 provides further details about SystemT ap. Red Hat Enterprise Linux 5 SystemT ap T apset Reference — T he SystemTap Tapset Reference for Red Hat Enterprise Linux 5 provides further details about SystemT ap. See Also Chapter 1, Red Hat Developer Toolset provides an overview of Red Hat Developer T oolset and more information on how to install it on your system. Chapter 11, SystemTap provides an introduction to SystemT ap and explains how to use it to monitor the activities of a running system. Chapter 12, Valgrind explains how to use Valgrind to profile applications and detect memory errors and memory management problems, such as the use of uninitialized memory, improper allocation and freeing of memory, and the use of improper arguments in system calls. Chapter 13, OProfile explains how to use OProfile to determine which sections of code consume the greatest amount of CPU time and why. 95 Red Hat D eveloper Toolset 2.x User Guide Part VII. Getting Help 96 Chapter 15. Accessing Red Hat Product D ocumentation Chapter 15. Accessing Red Hat Product Documentation Red Hat Product Documentation located at https://access.redhat.com/site/documentation/ serves as a central source of information. It is currently translated in 22 languages and for each product, it provides different kinds of books from release and technical notes to installation, user, and reference guides in HT ML, PDF, and EPUB formats. Below is a brief list of documents that are directly or indirectly relevant to this book. Red Hat Developer Toolset Red Hat Developer T oolset 2.1 Release Notes — T he Release Notes for Red Hat Developer T oolset 2.1 provide more information about this product. Red Hat Developer T oolset 2.1 Software Collections Guide — T he Software Collections Guide for Red Hat Developer T oolset 2.1 explains the concept of Software Collections and documents the scl tool. Red Hat Enterprise Linux Red Hat Enterprise Linux 6 Developer Guide — T he Developer Guide for Red Hat Enterprise Linux 6 provides detailed information about libraries and runtime support, compiling and building, debugging, and profiling. Red Hat Enterprise Linux 6 Installation Guide — T he Installation Guide for Red Hat Enterprise Linux 6 explains how to obtain, install, and update the system. Red Hat Enterprise Linux 5 Installation Guide — T he Installation Guide for Red Hat Enterprise Linux 5 explains how to obtain, install, and update the system. Red Hat Enterprise Linux 6 Deployment Guide — T he Deployment Guide for Red Hat Enterprise Linux 6 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 6. Red Hat Enterprise Linux 5 Deployment Guide — T he Deployment Guide for Red Hat Enterprise Linux 5 documents relevant information regarding the deployment, configuration, and administration of Red Hat Enterprise Linux 5. 97 Red Hat D eveloper Toolset 2.x User Guide Chapter 16. Contacting Global Support Services Unless you have a Self-Support subscription, when both the Red Hat Documentation website and Customer Portal fail to provide the answers to your questions, you can contact Global Support Services (GSS). 16.1. Gathering Required Information Several items of information should be gathered before contacting GSS. Background Information Ensure you have the following background information at hand before calling GSS: Hardware type, make, and model on which the product runs Software version Latest upgrades Any recent changes to the system An explanation of the problem and the symptoms Any messages or significant information about the issue Note If you ever forget your Red Hat login information, it can be recovered at https://access.redhat.com/site/help/LoginAssistance.html. Diagnostics T he diagnostics report for Red Hat Enterprise Linux is required as well. T his report is also known as a sosreport and the program to create the report is provided by the sos package. T o install the sos package and all its dependencies on your system, type the following at a shell prompt as root: yum install sos T o generate the report, run as root: sosreport For more information, access the Knowledgebase article at https://access.redhat.com/kb/docs/DOC3593. Account and Contact Information In order to help you, GSS requires your account information to customize their support, as well contact information to get back to you. When you contact GSS ensure you have your: Red Hat customer number or Red Hat Network (RHN) login name Company name Contact name Preferred method of contact (phone or email) and contact information (phone number or email address) 98 Chapter 16. Contacting Global Support Services Issue Severity Determining an issue's severity is important to allow the GSS team to prioritize their work. T here are four levels of severity. Severity 1 (urgent) A problem that severely impacts your use of the software for production purposes. It halts your business operations and has no procedural work around. Severity 2 (high) A problem where the software is functioning but production is severely reduced. It causes a high impact to business operations and no work around exists. Severity 3 (medium) A problem that involves partial, non-critical loss of the use of the software. T here is a medium to low impact on your business and business continues to function by utilizing a work around. Severity 4 (low) A general usage question, report of a documentation error, or a recommendation for a future product improvement. For more information on determining the severity level of an issue, see https://access.redhat.com/support/policy/severity. Once the issue severity has been determined, submit a service request through the Customer Portal under the Connect option, or at https://access.redhat.com/support/contact/technicalSupport.html. Note that you need your Red Hat login details in order to submit service requests. If the severity is level 1 or 2, then follow up your service request with a phone call. Contact information and business hours are found at https://access.redhat.com/support/contact/technicalSupport.html. If you have a premium subscription, then after hours support is available for Severity 1 and 2 cases. T urn-around rates for both premium subscriptions and standard subscription can be found at https://access.redhat.com/support/offerings/production/sla.html. 16.2. Escalating an Issue If you feel as though an issue is not being handled correctly or adequately, you can escalate it. T here are two types of escalations: T echnical escalation If an issue is not being resolved appropriately or if you need a more senior resource to attend to it. Management escalation If the issue has become more severe or you believe it requires a higher priority. More information on escalation, including contacts, is available at 99 Red Hat D eveloper Toolset 2.x User Guide https://access.redhat.com/support/policy/mgt_escalation.html. 16.3. Re-opening a Service Request If more relevant information regarding a closed service request (such as the problem reoccurring), you can re-open it via the Red Hat Customer Portal at https://access.redhat.com/support/policy/mgt_escalation.html or by calling your local support center, the details of which can be found at https://access.redhat.com/support/contact/technicalSupport.html. Important In order to re-open a service request, you need the original service request number. 16.4. Additional Resources For more information, see the resources listed below. Online Documentation Getting Started — T he Getting Started page serves as a starting point for people who purchased a Red Hat subscription, and offers the Red Hat Welcome Kit and Quick Guide to Red Hat Support for download. How can a RHEL Self-Support subscription be used? — A Knowledgebase article for customers with a Self-Support subscription. Red Hat Global Support Services and public mailing lists — A Knowledgebase article that answers frequent questions about public Red Hat mailing lists. 100 Changes in Version 2.1 Changes in Version 2.1 T he sections below document features and compatibility changes introduced in Red Hat Developer T oolset 2.1. A.1. Changes in Eclipse Red Hat Developer T oolset 2.1 is distributed with Eclipse 4 .3.1 and other plug-ins from the Eclipse Foundation's 2013 Eclipse Kepler 4.3 Service Release 1. T his version is newer than the version of Eclipse distributed with the previous release of Red Hat Developer T oolset, and provides a number of bug fixes and feature enhancements. Below is a comprehensive list of new features and compatibility changes in this release. For details on how to use these new features, see the built-in Eclipse documentation. A.1.1. Changes Since Red Hat Developer Toolset 2.0 T he following features have been added since the release of the Eclipse Platform and native plug-ins included in Red Hat Developer T oolset 2.0: T he Eclipse Platform has been updated from version 4.3.0 to 4.3.1. T his service release provides over 100 bug fixes and optimizations. T he Eclipse C/C++ Development T oolkit (CDT ) has been updated from version 8.2.0 to 8.2.1. T his service version update provides over 30 bug fixes and optimizations, including fixes related to the organization of include statements. Mylyn, a set of task and application life cycle management plug-ins, has been updated from version 3.9 to 3.9.1. T his update provides over 40 bug fixes and optimizations, including various improvements to the Bugzilla connector. EGit, a Git integration plug-in for Eclipse, has been updated from version 2.3.1 to 3.1. T his new major release includes: support for Mylin links in the History view, Git Staging view, and Com m it dialog window; improved Gerrit integration; a significantly enhanced Git Staging view; an enhanced command line tool (jgit); several performance improvements. T he Eclipse Linux T ools plug-in collection has been updated from version 2.0 to 2.2. T his update includes: support for the operf command line tool in the OProfile plug-in; the operf command is now used by default to make generic setup easier; an enhanced RPM Stubby plug-in, which is now able to generate RPM spec files from Perl makefiles, Ruby gamespec files, and Python setup.py files; an enhanced Spec File Editor plug-in, which is now able to download source files, prepare a buildroot, and also provides a Build menu, a corresponding toolbar, and improved support for hyperlinks in the editor; an enhanced SystemT ap .stp files editor, which now has improved formatting capabilities; improved SystemT ap graphing, which has been streamlined to be easier to launch and configure. A.2. Changes in GCC 101 Red Hat D eveloper Toolset 2.x User Guide Red Hat Developer T oolset 2.1 is distributed with GCC 4 .8.2, which provides a number of bug fixes over version 4.8.1 included in Red Hat Developer T oolset 2.0. T he Red Hat Developer T oolset 2.1 version of GCC does not introduce any new features or compatibility changes. A.3. Changes in elfutils Red Hat Developer T oolset 2.1 is distributed with elfutils 0.157, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and version 0.155 included in Red Hat Developer T oolset 2.0. Below is a comprehensive list of new features in this release. A.3.1. Changes Since Red Hat Developer Toolset 2.0 T he following features have been added since the release of elfutils included in Red Hat Developer T oolset 2.0: T he libdw library now supports new functions dwarf_getlocations(), dwarf_getlocation_attr(), and dwarf_getlocation_die(). T he dwarf_getlocation() function from the libdw library now supports new DWARF GNU extension opcodes DW_OP_GNU_param eter_ref, DW_OP_GNU_convert, DW_OP_GNU_reinterpret, DW_OP_GNU_regval_type, DW_OP_GNU_entry_value, DW_OP_GNU_deref_type, and DW_OP_GNU_const_type. T he dwfl_m odule_addrsym () function from the libdw library now returns the ST B_GLOBAL symbols in preference to ST B_WEAK. T he dwfl_report_elf() function from the libdw library now accepts an additional parameter. T his new parameter can be used to configure whether the start address specified in another parameter is an absolute address or a bias relative to the p_vaddr pointer from the program header of the given ELF file. Functions dwfl_m odule_getsym tab(), dwfl_m odule_getsym (), dwfl_m odule_addrsym (), and dwfl_m odule_addrnam e() from the libdw library are now aware of the existence of MiniDebugInfo files embedded in main ELF files and consult them when looking for symbols. T he dwfl_core_file_report() function from the libdw library now reads the chain from the DT _DEBUG entry before attempting to use other module discovery methods. T he eu-readelf utility now understands core note type values NT _ARM_T LS, NT _ARM_VFP, NT _ARM_HW_BREAK, NT _ARM_HW_WAT CH, NT _SIGINFO, and NT _FILE and converts them to a human-readable form. It also understands .gdb_index sections version 8. T he eu-readelf utility now supports the following new command line options: T he --elf-section option can be used to inspect an embedded ELF file. T he --unresolved-address-offsets option or its short variant -U can be used to dump addresses in ELF files without resolving them to symbols. T he --debug-dum p=decodeline option can be used to dump a .debug_line section in a human-readable, expanded format. In contrast, the original behavior of --debugdum p=aranges can now be achieved by using the --debug-dum p=decodedaranges option, and the default formatting of the .debug_aranges section is now the same as in the ELF file. T he eu-addr2line utility now supports a new command line option --inlines (and its short variant -i), which can be used to display all inlined subroutines of a particular address. A.4. Changes in Git Red Hat Developer T oolset 2.1 is distributed with Git 1.8.4 , which provides a number of bug fixes and 102 Changes in Version 2.1 Red Hat Developer T oolset 2.1 is distributed with Git 1.8.4 , which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version. Below is a comprehensive list of new features in this release. A.4.1. Changes Since Red Hat Enterprise Linux 6.5 T he features below have been added since the release of Git included in Red Hat Enterprise Linux 6.5. General Changes in the Git Suite Git now detects the DISCOVERY_ACROSS_FILESYST EM environment variable to decide whether to stop at a filesystem boundary when looking for the .git directory. T he GIT _ASKPASS environment variable can now be used to tell commands from the Git suite that prompt for password to use an external program. T he contents of the /etc/m ailnam e file (if it exists) are now the default source of email hostnames for both the committer and the author. Conflict markers in the diff3 style now have a label. T he core.whitespace configuration variable can now use a new rule: tab-in-indent. T his rule treats a tab character at the beginning of a line as an error (useful for projects with space-only indents, for example, Python projects). T he core.eol configuration variable is now the end-of-line authority over the working-tree files. It accepts the lf, crlf, or native values. T he default is set to native. Git now reports any corrupt objects it finds. A dash (“-”) is no longer a valid character at the beginning of a branch or tag name. T he pager.subcommand configuration variable now allows for setting a different pager for each subcommand. T he core.abbrev configuration variable can now be used to set the minimum length of abbreviated and unique object names. Git now recognizes MAT LAB function and header patterns. Git now supports output coloring. A large number of configuration options have been added to allow for a separate tweaking of the look of various parts of outputs. Git commands now ignore the .gitm odules file if it is currently conflicted in a merge. T he -c name=value command line option can now be used to override a configuration option. T he core.attributesfile configuration variable can be set to a path of a file containing fallback default attributes. T he default value is /etc/gitattributes. A new command, git check-ignore, has been added. T he command helps to debug .gitignore files by showing the pattern on the basis of which individual files are included or excluded. T he Git login shell for SSH accounts can now be extended by the user's own custom commands. A new configuration variable, advice.statusHints, is now available. It allows the user to disable (or enable) the hints about staging, unstaging, or adding files displayed by the git status command. A new credential helper has been added to access the GNOME Keyring and other services. Commands using some form of authentication can now use it to communicate with external programs. Refer to gitcredentials(7) for more information on configuring credential helpers. Git can now be told to interpret paths literally. T he --literal-pathspecs command line option serves that purpose. Setting the GIT _LIT ERAL_PAT HSPECS environment variable to 1 has the same effect. T he .gitignore file now accepts the “**” (double asterisk) recursive glob pattern. 103 Red Hat D eveloper Toolset 2.x User Guide Regular expressions are now accepted in the :/<string> notation. Also, the expression is no longer bound to the start of the commit log message. Note that this change is not backward compatible. Custom messages are now issued to users who are attempting to interactively connect to the git shell when the interactive access is disabled. Git subcommands now honor the i18n.* configuration variables when handling text. See gitconfig(1) for more information on these settings. A considerable number of new scripts have been added to the contrib/ directory. T he git fsck and git prune commands are now reporting on their progress. T he http.useragent configuration variable can now be set to lie to your firewall about the client used for HTTP connections. A new command, git check-m ailm ap, has been added. It can be used to map author and committer names and email addresses to their preferred names and addresses as specified in the .m ailm ap file. Users can now switch between commits with and without a submodule without re-cloning it due to improved plumbing — the GIT _DIR metainformation directory for submodules is set up inside a new submodule's directory. Whenever a date is expected as an argument, users can now specify a timezone designator format without seconds and with a colon between hours and minutes. T he GIT _PREFIX environment variable is now available in the environments of processes spawned in configuration, so that they can check where in the tree the original command was invoked. A special path specification, “:/”, can be used to tell subcommands that work only with the current directory to work with the entire working tree. T he git am Command T he git am command now accepts patches created by Mercurial. T he git am command now sanitizes occurrences of “Re:” in the subject line. T he following new command line options have been added to the git am command: --exclude=path Passed to the git apply command that is used in the background to apply the patch. --keep-cr Handles lines that contain a carriage return character (CR). T he git apply Command T he --verbose (or -v) command line option now reports offsets in case a patch does not apply cleanly. T he git archive Command It is now possible to pipe the output of the git archive command to the gzip command. Do this by passing the tar.gz or tgz arguments to the --form at command line option or by specifying either of these arguments in the tar.format configuration variable. T he git bisect Command T he result of the git bisect command is now output as a comment in the bisect log file. 104 Changes in Version 2.1 T he git blame Command T he git blam e command now applies the configured textconv filters whenever possible. T he textconv conversion allows git blam e to present a human-readable output even when working with binary files. T he following new command line options have been added to the git blam e command: --abbrev[=n] Display n+1 hexadecimal digits instead of the default 7+1 as the abbreviated object name. --line-porcelain Use the easily parsable porcelain-formatted output, but show commit information for each line. T his option implies the use of the --porcelain option. For a description of the porcelain format, see git-blam e(1). --show-em ail (or -e) Display email addresses instead of author names. T his option is set to off by default. T he git branch Command T he following new command line options have been added to the git branch command: --edit-description Open an editor to describe the purpose of the branch. --list List existing branches. T he option optionally accepts a globbing pattern. T he git checkout Command T he following new command line options have been added to the git checkout command: -B it A shorter version of running git branch -f it followed by git checkout it. See gitbranch(1) for more information. --detach commit A more user-friendly equivalent of the default behavior of git commit. --no-overwrite-ignore Do not overwrite untracked or ignored files during a merge. --orphan newbranch Creates a newbranch similarly to the git checkout -b newbranch command but with a detached root commit. 105 Red Hat D eveloper Toolset 2.x User Guide T he git check-attr Command T he git check-attr command now accepts relative paths passed from the command line. T he following new command line options have been added to the git check-attr command: --all (or -a) List all the attributes of the specified path. --cached Look at the .gitattributes file in the index, and ignore the working tree. T he git cherry-pick Command T he git cherry-pick command is now aware of commits that failed to apply. A range of commits can now be picked. A custom merge strategy can now be set. See below for a description of the new --strategy command line option. After resolving conflicts with git cherry-pick -s, sign-off lines are now implicitly left untouched in the log template. T he following new command line options have been added to the git cherry-pick command: --abort Abort current operation and return to the state before the start of the sequence. --allow-em pty-m essage Prevents the git cherry-pick command from failing when a commit is being picked that has no log message. --continue Continue the operation in progress. T his option uses information found in the .git/sequencer file and can be used after conflict resolutions. --strategy=strategy Specifies the merge strategy for three-way merges. T his option should only be used once. For information about the available strategies, see git-m erge(1). T he git clean Command T he git clean command now provides an interactive mode, which can be invoked using the -interactive (or -i) command line option. For a description of subcommands available in the interactive mode, see git-clean(1). A new command line option, --exclude=pattern (or -e pattern), has been added. T his option allows the user to define rules that specify which files to ignore (in addition to what is defined in the .gitignore and GIT _DIR/info/exclude files). T he git clone Command A new command line option, --config key=value (or -c key=value), is now available. T his option sets the specified configuration variable to be in effect at the time of the initial checkout. T he syntax expected is the same as what is used with the git config command. 106 Changes in Version 2.1 T he git commit Command T he git com m it command now accepts arguments in the form of relative paths that point outside of the current directory. Aborting interactive mode (initialized by the --interactive command line option) now discards all changes that were made in it. It is now possible to set the com m it.cleanup configuration variable to whitespace, which is equivalent to running the git com m it command with the --cleanup=whitespace command line option. For a description of all available cleanup modes, see git-com m it(1). T he following new command line options have been added to the git com m it command: --fixup=commit Prefix the commit line with “fixup! ”. T his option is used when running the git rebase -autosquash command. --gpg-sign[=keyid] (or -S[keyid] Sign the commit using the specified GPG key. --no-edit Do not launch an editor for the commit message. When used with the --am end command line option, it only updates the commit tree, not the commit message. --patch (or -p) Select patch hunks for committing using the interactive interface. Refer to git-add(1) for more information about the interactive mode. --squash=commit Prefix the commit line with “squash! ”. T his option is used when running the git rebase -autosquash command. T he git count-objects Command T he verbose output, invoked by passing the --verbose (or -v) command line option to the git count-objects command, now reports on various garbage in the .git directory. Refer to git-count-objects(1) for a more detailed description of the verbose output. A new command line option, --hum an-readable (or -H), has been added. T his option makes git count-objects show sizes in a human-readable format. T he git cvsimport Command A new command line option, -R, has been added to git cvsim port. T his option creates a mapping between CVS revisions and Git commits. Users of the git cvsim port command can now use the following configuration variables to enable certain command line options by default: Configuration Variable Command Line Option Description cvsim port.authorsFil es -A file_name Maps CVS user names to full names and email addresses. cvsim port.ignorePath s -S regular_expression Skips paths that match a certain regular expression. cvsim port.m ergeRegex -M regular_expression Parses commit messages in order to 107 Red Hat D eveloper Toolset 2.x User Guide detect merge commits. cvsim port.trackRevis ions -R Creates a mapping between CVS revisions and Git commits. T he git cvsserver Command T he git cvsserver can now use pserver to offer CVS access. Refer to git-cvsserver(1) for information on how to configure this. T he git daemon Command T he git daem on server can now listen on multiple addresses. T he daemon now allows for external hooks via the --access-hook=path command line option. T his option executes an external command specified by path every time a client connects to the daemon. T he git describe Command A new command line option, --first-parent, has been added. T his option instructs the git describe command to only follow the first parent commit in case of merge commits. T he git diff Command T he --subm odule command line option is now able to notice ‘dirty’ submodules. T hese are submodules that contain modified or untracked files. T he regular expression for function headers now detects visibility modifiers (public, private, or protected) in the PHP5 programming languages. Functions and subroutines of the Fortran, Pascal, and Perl programming languages are now recognized. A new configuration variable, diff.subm odule, is now available for setting the default format used for showing differences in submodules using the --subm odule command line option. T he option can have two values: log or short. For a detailed description of the two values, see git-diff(1). T he default value is short. A new configuration variable, diff.noprefix, is now available for setting an implicit behavior identical to what the --no-prefix command line option does. If set, no source or destination prefix is shown. A new configuration variable, diff.context, is now available for setting the number of lines shown above and below the modified line or lines. T he default value is 3. T he --unified (or -U) option overrides this setting. A new configuration variable, diff.algorithm , is now available. T his variable can be used to specify the algorithm used to display the git diff output. It accepts the following arguments: default or m yers, m inim al, patience, and histogram . For a description of the different algorithms, refer to git-diff(1). T he default value is default or m yers. A new configuration variable, diff.ignoresubm odules, is now available. T his variable can be used to ignore submodules when generating diffs. T he following new command line options have been added to the git diff command: --function-context (or -W) Displays entire functions in the context of changes. --histogram 108 Changes in Version 2.1 Generates output using the histogram algorithm. T his algorithm supports low-occurrence common elements and offers better performance than the default. --ignore-blank-lines T ells git diff to ignore changes that consist only of additions or removals of blank lines. --m inim al Generates output using the minimal algorithm. T his algorithm attempts to minimize the output at the cost of extra time spent. --stat-count Limits the length of output to the number of lines specified by the option. Lines exceeding the limit are substituted with “...”. --word-diff=mode Shows added or removed words. T his option accepts color, plain, porcelain, and none as modes. For a description of the available modes, refer to git-diff(1). T he default is plain. T he git fetch Command T he git fetch command now honors the transfer.fsckobjects configuration variable. If set, the command validates received objects. A new command line option, --recurse-subm odules[=argument], has been added. T his option controls whether to fetch new commits from submodules too. T his option accepts the yes, no, or ondem and arguments. If passed without an argument, it assumes yes. For a description of the arguments, see git-fetch(1). T he git format-patch Command T he git form at-patch command now accepts the --subject-prefix command line option with no argument. T his option substitutes the standard “[PAT CH]” prefix in the subject line with a new prefix (or none) specified on the command line. T he form at.coverLetter configuration variable may now be used to turn the --cover-letter command line option on or off. T he form at.coverLetter may further be set to auto to only be used with sets of two or more commits. T he following new command line options have been added to the git form at-patch command: --from [=whom] Set the “From: ” field to the specified person. Not to be used when preparing patches for the git send-m ail command. See git-form at-patch(1) for more information about the behavior of this option. --notes[=ref] Add notes to the formatted patch. Refer to git-notes(1) for more information on the way Git handles these notes. --[no-]signature Alter the email signature used in the output messages. T he form at.signature configuration variable can be used to set the default signature. When neither the command line option nor the configuration variable is specified, the Git version number is used as the 109 Red Hat D eveloper Toolset 2.x User Guide signature. T he --no-signature variant of the option can be used to prevent the inclusion of any signature. --quiet (or -q) Do not show the names of the generated patch files. --reroll-count=n (or -v n) Output a set of patches with the n version string prepended to their names and the version mentioned in the subject. T he git for-each-ref Command T he git for-each-ref command now recognizes the following new fields for extracting values from referenced objects into the resulting output: %(sym ref), %(sym ref:short), %(flag), %(objectnam e:short), %(contents:subject), %(contents:body), and %(contents:signature). T he git grep Command Functions and subroutines of the Fortran, Pascal, and Perl programming languages are now recognized. It is now possible to pass the - (dash) argument to the -f command line option to instruct it to read patterns from the standard input. T he following new command line options have been added to the git grep command: --break Delimit matches from different files with an empty line. --color=[when] Color the matches returned by git grep. T his option accepts the auto, always, or never arguments. T he default setting is always. --exclude-standard Do not search in files listed in the .gitignore file when using the --no-index option. --function-context (or -W) Show the entire function in which the match was found. --heading Print the filename above the matches from that file instead of showing the file information for each match separately. --no-index In the current directory, search also for matches in files that are not managed by Git. --open-files-in-pager [pager] (or -O [pager]) Instructs git grep to open files with matching regular expressions in the user's pager or editor of choice. -P Instructs git grep to expect and accept Perl-compatible regular expressions. 110 Changes in Version 2.1 --untracked In the current tree, search in both tracked and untracked files. T he git hash-object Command T he --stdin-paths command line option can now be used together with the --no-filter option. T his results in the git hash-object command reading filenames from the standard input and hashing the contents as is — disregarding any filters that may have been applied by the attributes mechanism. T he git help Command T he --web (or -w) command line option now works with the Chrome and Chromium web browsers. T he default web browser can be specified using the help.browser or web.browser configuration variables. If none of these variables is defined, the git web--browse script attempts to choose a browser automatically. A new command line option, --guides (or -g), has been added. T his option shows a list of useful guides. T he git imap-send Command T he git im ap-send command now supports CRAM-MD5 as a valid method for authentication with an IMAP server. T he git init Command A new configuration variable, init.tem platedir, is now recognized. Similarly to the --tem plate command line option and the GIT _T EMPLAT E_DIR environment variable, it specifies the directory containing files and directories that will be copied to the .git directory (or GIT _DIR). A new command line option, --separate-git-dir=gitdirectory, has been added. T his option forces git init to initialize the repository in the specified location. A symbolic link is created in place of the .git directory, pointing to the separately placed repository. T he git log Command T he --follow command line option now follows copies as well as renames when listing the history of a file. T he git log commands are now able to interpret paths specified using globs. T he --form at=format option is now able to interpret the %g[nNeE] specifiers when showing information from reflogs. For a description of the specifiers, see git-log(1). T he --decorate command line option now shows commit information in colors. It is now also capable of highlighting grafted and replaced commits. T he following new command line options have been added to the git log command: --author-date-order Sort the commits listed based on the author timestamp. No parents are shown before all of their children are listed. --cherry Display two diverged branches, and omit any changes they share. T his is equivalent to the following combination of options: --right-only --cherry-m ark --no-m erges. 111 Red Hat D eveloper Toolset 2.x User Guide --cherry-m ark Display two diverged branches, and mark any changes they share with the “=” (equal sign) character. --children List also the children of commits. -Gpattern Only match changes that contain pattern. --grep-reflog=pattern Limit the output to commits whose reflog messages match pattern. If multiple --grepreflog options are used, commits with reflog messages matching any of the patterns specified are listed. T his option should only be used together with the --walk-reflogs option. -Lstart,end:file Show the changes that the line specified by the range within the file went through. Either end of the range may be specified by absolute line numbers or regular expressions. T he end of the range may also be an offset that specifies a number of lines before or after start. --notes Replaces the --show-notes option. T his option shows the notes annotating the commits (commit log messages). --show-signature Pass the signature of a commit object to the gpg --verify command to check its validity, and show the output. --use-m ailm ap Rewrite the names and email addresses of committers in the output using the m ailm ap file. T he git ls-remote Command A new command line option, --exit-code, has been added. T his option returns 2 as the command's exit code when no matching remote refs are found. A new command line option, --help, has been added. T his option displays basic information about the syntax and options of the git ls-rem ote command. T he git merge Command T he --log[n] command line option may now be optionally given a numeric parameter. T he parameter specifies the number of commits merged from which one-line descriptions will be used in the log message in addition to branch names. It is now possible to use the git m erge - command, where - (dash) denotes the name of the previous branch. T he m erge.ff configuration variable can now be set to yes, no, or only to specify the default behaviour, which corresponds to the --ff, --no-ff, and --ff-only command line options respectively. For a description of these options, see git-m erge(1). 112 Changes in Version 2.1 T he following new command line options have been added to the git m erge command: --abort Abort the current conflict-resolution process, and attempt to go back to the pre-merge state. It may not be possible to go back if there were uncommitted changes when the merge was started. --edit (or -e) Open an editor to edit the automatically generated merge message before committing a successful merge. --no-overwrite-ignore Do not overwrite untracked or ignored files during a merge. --[no-]verify-signature Verify the GPG signatures of the commits that are being merged. Abort the merge if the verification fails. T he --no-verify-signature variant of the option instructs the git m erge command not to verify commit signatures. T he git mergetool Command T he git m ergetool command now instructs the vim or gvim editors to show the three-way diff by default. T he old behavior can be achieved by specifying vim diff2 or gvim diff2 as the tool to be used. T he git merge-base Command A new command line option, --is-ancestor commit commit, has been added. T his option returns the 0 exit status code if the first commit is an ancestor of the second commit and 1 if not. T he git merge-file Command A custom conflict-marker size can now be used. T he custom size can be set using the --m arkersize command line option or the conflict-m arker-size configuration attribute. T he union merge behaviour can now be used. T his means that git m erge-file resolves conflicts by concatenating lines from both sides of the merge. T he git notes Command A new subcommand, git notes m erge, is now available. T his subcommand attempts to merge notes accompanying the specified object into the current notes ref. T he git notes prune Subcommand T he following new command line options have been added to the git notes prune subcommand: --dry-run (or -n) Does not remove anything. Instead, it only lists the names of objects whose notes would be pruned. --verbose (or -v) Makes the prune subcommand provide more information when merging notes and report all 113 Red Hat D eveloper Toolset 2.x User Guide names of objects whose notes are removed during the pruning. T he git pull Command T he git pull command can now pull an annotated or signed tag instead of a branch tip. T he GPG signature of the tag is then made a part of the merge commit. T he pull.rebase configuration variable is now recognized. It makes git pull act as if the -rebase command line option was passed. T he variable serves as a fallback setting in case the perbranch branch.name.rebase variable is not set. Note that this may be a potentially dangerous setting. Refer to git-rebase(1) for more information about rebasing and to git-config(1) for a description of the pull.rebase variable. T he --verbose (or -v) and --quiet (or -q) command line options are now passed along to the git rebase command when git pull --rebase is run or when the corresponding branch.name.rebase configuration variable is set. A new command line option, --[no-]verify-signature, has been added. T his option verifies the GPG signatures of the commits that are being merged and aborts the merge if the verification fails. T he --no-verify-signature variant of the option instructs the git pull command not to verify the GPG signatures of the commits. T he git push Command A new “pre-push” hook is available. If the hook exits with a non-zero status code, it will prevent the git push command from performing any operations. T o enable the hook, pass the --verify command line option to git push. Use the --no-verify option to bypass the hook. For a more detailed description of the hook, refer to githooks(5). T he --force (or -f) command line option is now required for updating remote tags. Note that forcing a push can result in a loss of commits in the remote repository if not used with care. For a more detailed description of this option, refer to git-push(1). T he push.default configuration variable has a new valid value of upstream , which is synonymous to the now deprecated tracking value. For a description of the available push.default values, refer to git-config(1). T he following new command line options have been added to the git push command: --follow-tags Push annotated tags plus all the refs that would be pushed normally. --recurse-subm odules=check|on-dem and Do not push if any submodule is ahead of its remote HEAD. See git-push(1) for an explanation of the two possible arguments. T he git read-tree Command A new command line option, --dry-run (or -n), has been added. T his option checks if a merge would complete without errors when the git read-tree command is passed the -m option. T he git rebase Command T he rebase.autosquash configuration option is now honored by the git rebase -interactive command. T he --interactive (or -o) command line option prepares a list of the 114 Changes in Version 2.1 commits to be rebased and lets the user modify that list before the rebasing takes place. T he git rebase command now updates reflog for HEAD even when it finishes normally or is ended with the --abort command line option. It is now possible to pass SHA-1 hashes as object names when using the --autosquash command line option. T he --strategy-option=option (or -X option) command line option can now be used along with the --strategy=strategy (or -s strategy) option to pass options to the selected merge strategy. Refer to git-rebase(1) for a description of the available strategies. T he following new command line options have been added to the git rebase command: --edit-todo Edit the instructions in an editor when using the interactive mode (invoked by the -interactive (or -i) option). --[no-]autostash T emporarily stash uncomitted changes before the rebasing begins instead of refusing to run. T he --no-autostash variant of the option may be used to prevent autostashing when the rebase.autostash configuration variable is set. T he git remote Command A new subcommand, git rem ote set-branches, is available. T his subcommand modifies the list of branches tracked by the specified remote. T he git replace Command T he --delete (or -d) command line option now interprets its object argument as the extended SHA-1 syntax. T he object may now be specified, for example, as HEAD~NUM. T he git rerere Command A new subcommand, git rerere rem aining, is now available. It displays conflicts that have not been automatically resolved. T his includes paths that the git rerere command cannot track, such as submodules. T he git rerere forget subcommand now requires a path to be specified where any conflict resolutions are to be reset. T he git reset Command A new command line option, --keep, has been added. T his option discards index entries and commits in the working tree but preserves local changes. T he git revert Command A new command line option, --strategy=strategy, has been added. T his option specifies the merge strategy for three-way merges. T his option should only be used once. For information about the available strategies, see git-m erge(1). T he git send-email Command T he git send-em ail command is now able to parse and use the “T o:” field from its input files. 115 Red Hat D eveloper Toolset 2.x User Guide T he value of the sendem ail.aliasfile configuration variable may now begin with the “~” (tilde) character to denote the user's home directory. T he sendem ail.annotate configuration variable may now be used to set the default behavior that is otherwise controlled by the --annotate command line option. If set to true, each patch that is about to be sent is offered for review and editing. Patches sent with the --in-reply-to command line option are now replies to the new cover letter that begins the new thread. T he following new command line options have been added to the git send-em ail command: --help (or -h) Display basic information about the syntax and options of the git send-em ail command. --to-cm d=command T his option is similar to the --cc-cm d=command option and can be used to read the list of recipients from the output of the command. T he git show Command T he git show --do-walk -n command now has a more compact equivalent, git show -n. Refer to git-rev-list(1) for more information on object traversal. T he --no-patch command line option is a new synonym for the -s option. T his option suppresses diff output. It can also be used to cancel the effect of the --patch option. T he git show-ref Command T he --head command line option now always means the “HEAD” reference, regardless of filtering. T he git stash Command A new command line option, --include-untracked (or -u), has been added. T his option stashes untracked files as well, which allows for them to be cleaned later by the git clean command. T he git status Command T he git status command now detects submodules with uncommitted local changes in their working tree. Users can now change the value of the status.short configuration variable to true to configure the git status command to use the --short command line option by default. Similarly, it is now possible to change the value of the status.branch configuration variable to true to run git status with the --branch option by default. T he following new command line options have been added to the git status command: --branch (or -b) Displays the name of the current branch even when the --short (or -s) option is used. --ignore-subm odules[=condition] T his option accepts none, untracked, dirty, or all as an optional argument and can be used to ignore certain changes to submodules. --ignored Displays ignored files. 116 Changes in Version 2.1 T he git submodule Command Users are now allowed to create shallow clones of submodule repositories. Users can now run git subm odule commands from any part of the working tree. T he git subm odule sync command now also updates information for submodules that have not been checked out. T he git subm odule update command no longer terminates immediately when it encounters an error. Instead, it updates the remaining registered submodules and displays the error message on exit. T he git subm odule update command can now be configured to execute an arbitrary shell command. T o enable this behavior for a particular submodule, change the value of the subm odule.submodule_name.update configuration variable to any shell command that accepts exactly one command line argument. Users can now set the value of the subm odule.submodule_name.update configuration variable to none to prevent a particular submodule from being updated by default. A new command, git subm odule deinit, has been added. T his command unregisters selected submodules and serves as a counterpart to the git subm odule init command. A new command line option, --force (or -f), has been added to git subm odule. T his option can be used to discard local changes. A new command line option, --nam e, has been added to git subm odule. T his option can be used to specify the name of a new submodule. It is now possible to apply the --recursive command line option to the sync command of git subm odule. T his option makes sync traverse nested submodules recursively. T he git tag Command A new command line option, --cleanup=mode, has been added. T his option controls the way whitespace is handled in tag messages. It accepts the verbatim , whitespace, or strip arguments. See git-tag(1) for a description of what the available modes do. T he gitweb Interface T he configuration of the gitweb interface can now be changed after each request. T he /etc/gitweb-com m on.conf configuration file is now read if it exists. T he gitweb interface is now able to show diffs. Other new subcommands and exotic option combinations T he following subcommands and exotic option combinations have been added: git rem ote -t branch --m irror=fetch T his is now a legal combination of options as the mirroring in the fetch mode no longer mirrors everything. git rev-list A..B --ancestry-path T he newly available --ancestry-path option excludes commits that are not descendants of commit A. 117 Red Hat D eveloper Toolset 2.x User Guide git rev-list --count --cherry-m ark T his combination now produces a more useful output as it counts the cherry-picked commits separately. A.5. Changes in GDB Red Hat Developer T oolset 2.1 is distributed with GDB 7.6.1, which provides a number of bug fixes over the Red Hat Enterprise Linux system version and version 7.6 included in Red Hat Developer T oolset 2.0. Below is a comprehensive list of new features in this release. A.5.1. Changes Since Red Hat Developer Toolset 2.0 T he following features have been added since the release of GDB included in Red Hat Developer T oolset 2.0: It is now possible to use the ClassName::MemberVariable expression to access non-static member variables of a particular class in the current scope of implicit parameter this. GDB now automatically loads files with the .gdb and .py file extension located in the /opt/rh/devtoolset-2/root/etc/gdbinit.d/ directory on startup. A.6. Changes in Valgrind Red Hat Developer T oolset 2.1 is distributed with Valgrind 3.8.1, which provides a number of bug fixes over the version included in Red Hat Developer T oolset 2.0. Below is a comprehensive list of new features in this release. A.6.1. Changes Since Red Hat Developer Toolset 2.0 T he following features have been added since the release of Valgrind included in Red Hat Developer T oolset 2.0: Manual pages cg_diff(1), cg_merge(1), valgrind-listener(1), and vgdb(1) have been added. Support for PT RACE_GET _T HREAD_AREA and PT RACE_SET _T HREAD_AREA has been added. Valgrind now supports AF_BLUET OOT H sockets. Valgrind now supports the SSE4 MOVNT DQA instruction. A.7. Changes in OProfile Red Hat Developer T oolset 2.1 is distributed with OProfile 0.9.8, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version. Below is a comprehensive list of new features in this release. A.7.1. Changes Since Red Hat Developer Toolset 2.0 T he following features have been added since the release of OProfile included in Red Hat Developer T oolset 2.0: OProfile now supports the Intel Core i3, Intel Core i5, Intel Core i7, Intel Xeon Processor E3, Intel Pentium, and Intel Celeron processors formerly code-named Haswell. Users can now use named unit masks for Intel processors. 118 Changes in Version 2.0 Changes in Version 2.0 T he sections below document features and compatibility changes introduced in Red Hat Developer T oolset 2.0. B.1. Changes in Eclipse Red Hat Developer T oolset 2.0 is distributed with Eclipse 4 .3 and a wide selection of plug-ins from the Eclipse Foundation's 2013 Eclipse 4.3 “Kepler” release, and provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version. Below is a comprehensive list of new features and compatibility changes in this release. For details on how to use these new features, see the built-in Eclipse documentation. B.1.1. Changes Since Red Hat Enterprise Linux 6.4 T he following features have been added since the release of the Eclipse Platform and native plug-ins included in Red Hat Enterprise Linux 6.4: T he Eclipse Platform has been updated from version 3.6 to 4.3. T his new major release features a more flexible user interface based on Eclipse Modeling Framework (EMF), CSS-based themes, dependency injection, and more. T he Eclipse C/C++ Development T oolkit (CDT ) has been updated from version 7.0 to 8.2. T his new major release includes: a greatly enhanced indexer, both in terms of capabilities and speed; improved GNU Debugger integration; support for GNU Debugger's pretty-printing; multi-process debugging; project-less debugging; enhanced refactoring; code-checking capabilities; an improved and more polished user interface. Mylyn, a set of task and application life cycle management plug-ins, has been updated from version 3.4 to 3.9. T his update includes: an enhanced task-focused interface and task editing; a new Jenkins/Hudson connector; enhanced Bugzilla and T rac connectors; EPUB authoring tools. A new EGit plug-in has been added. T his plug-in includes an Eclipse T eam provider based on JGit, a Git implementation written entirely in Java, and adds support for the Git revision control system to the Eclipse user interface by introducing the History and Synchronize views, Com pare and Quick Diff menu items, and various wizards to make it easier for developers to use this plug-in. New GCov integration has been added to allow the user to visualize GCov output in both summarized form and in file editors. As well, graphing capabilities for the data have been added. New GProf integration has been added to allow the user to view profiling information such as execution time and call graphs. As well, graphing capabilities for the data have been added. A new SystemT ap integration plug-in has been added. T his plug-in includes: an editor for the .stp files with the autocomplete feature; the Probe view with a list of probes that are available on the system; 119 Red Hat D eveloper Toolset 2.x User Guide the Function view with a list of functions that are available on the system and can be used in .stp scripts. As well, this plug-in includes integration for running SystemT ap scripts and viewing the results in a textual, tabular, and graphical manner. Note that the result sets are updated in a near-runtime way, which allows the user to use this plug-in for longer-running monitoring tasks. New kernel perf tool integration has been added. T his plug-in uses the performance counters subsystem of the Linux kernel to profile applications, makes it easier to analyze the results by hyperlinking to the sources in the workspace projects, simplifies the perf tool configuration by selecting the counters to be used, and allows the user to run this tool remotely. A unified profiling launcher has been added to provide a single method to launch profiling. It allows the user to select a profiling category (Mem ory, T im ing, or Coverage) and back ends for this category (such as OProfile, perf, or GProf for T im ing). T he C/C++ documentation plug-in has been enhanced to recognize and use gtk-doc generated documentation and to display it in the Eclipse Help Center. T he OProfile plug-in has been enhanced to support root privilege authentication through polkit. T his feature is configured automatically. T he Valgrind plug-in now supports the Helgrind tool, which can be used to detect synchronization problems such as race conditions, deadlocks caused by incorrect locking order, or misuse of the POSIX pthreads API. When a problem is detected, the plug-in displays error markers on the corresponding lines in the source code. B.2. Changes in GCC Red Hat Developer T oolset 2.0 is distributed with GCC 4 .8, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of new features and compatibility changes in this release. B.2.1. Changes Since Red Hat Developer Toolset 1.1 T he following features have been added since the release of GCC included in Red Hat Developer T oolset 1.1. B.2.1.1. Caveats Aggressive Loop Optimizations T he loop optimizer of GCC has been improved to use language constraints in order to derive bounds for the number of iterations of a loop. T he bounds are then used as a guide to loop unrolling, peeling, and loop exit test optimizations. T he optimizations assume that the loop code does not invoke undefined behavior by, for example, causing signed integer overflows or making out-of-bound array accesses. For example, consider the following code fragment: 120 Changes in Version 2.0 unsigned int foo() { unsigned int data_data[128]; for (int fd = 0; fd < 128; ++fd) data_data[fd] = fd * (0x02000001); // error return data_data[0]; } When the value of the fd variable is 64 or above, the fd * 0x02000001 operation overflows, which is invalid in both C and C++ for signed integers. In the example above, GCC may generate incorrect code or enter an infinite loop. T o fix this error, use the appropriate casts when converting between signed and unsigned types to avoid overflows, for instance: data_data[fd] = (uint32_t) fd * (0x02000001U); // ok If necessary, this optimization can be turned off by using the new command line option -fnoaggressive-loop-optim izations. B.2.1.2. General Improvements and Changes New Local Register Allocator GCC 4.8 features a new Local Register Allocator (LRA), which replaces the 26-year old reload pass and improves the quality of generated code. T he new local register allocator is meant to be simpler, easier to debug, and does a better job of register allocation. AddressSanitizer A fast memory error detector called AddressSanitizer has been added and can be enabled by using the -fsanitize=address command line option. It augments memory access instructions in order to detect use-after-free and out-of-bound accesses to objects on the heap. T hreadSanitizer A fast data race detector called ThreadSanitizer has been added in GCC 4.8. T he option to enable this feature is -fsanitize=thread. Compiling Extremely Large Functions Many scalability bottlenecks have been removed from GCC optimization passes. As a consequence, it is now possible to compile extremely large functions with smaller memory consumption in less time. New -Og Optimization Level A new general optimization level, -Og, has been introduced. T his optimization level addresses the need for fast compilation and a superior debugging experience while providing a reasonable level of runtime performance. Overall, the development experience should be better than the default optimization level O0. Caret Diagnostic Messages T he diagnostic messages of GCC, which display a line of source code, now also show a caret that indicates the column where the problem was detected. For example: 121 Red Hat D eveloper Toolset 2.x User Guide fred.cc:4:15: fatal error: foo: No such file or directory #include <foo> ^ compilation terminated. New -fira-hoist-pressure Option A new command line option, -fira-hoist-pressure, has been added. T his option uses the register allocator to help decide when it is worthwhile to move expressions out of loops. It can reduce the size of the compiler code, but it slows down the compiler. T his option is enabled by default at -Os. New -fopt-info Option A new command line option, -fopt-info, has been added. T his option controls printing information about the effects of particular optimization passes, and takes the following form: -fopt-info[-info][=file_name] T he info part of the option controls what is printed. Replace it with optim ized to print information when optimization takes place, m issed to print information when optimization does not take place, note to print more verbose information, or optall to print everything. Replace file_name with the name of the file in which you want the information to be written. If you omit this part of the option, GCC writes the information to the standard error output stream. For example, to display a list of optimizations that were enabled by the -O2 option but had no effect when compiling a file named foo.c, type: gcc -O2 -fopt-info-missed foo.c New -floop-nest-optimize Option A new command line option, -floop-nest-optim ize, has been added. T his option enables an experimental ISL-based loop nest optimizer, a generic loop nest optimizer that is based on the Pluto optimization algorithms and that calculates a loop structure optimized for data-locality and paralelism. For more information about this optimizer, see http://pluto-compiler.sourceforge.net. Hot and Cold Attributes on Labels T he hot and cold function attributes can now also be applied to labels. Hot labels tell the compiler that the execution path following the label is more likely than any other execution path, and cold labels convey the opposite meaning. T hese attributes can be used in cases where __builtin_expect cannot be used, for instance with a computed goto or asm goto. B.2.1.3. Debugging Enhancements DWARF4 DWARF4 is now used as the default debugging data format when generating debugging information. T o get the maximum benefit from this new debugging representation, use the latest version of Valgrind, elfutils, and GDB included in this release. New -gsplit-dwarf Option A new command line option, -gsplit-dwarf, has been added. T his option tells the compiler driver to separate as much DWARF debugging information as possible into a separate output file with the .dwo 122 Changes in Version 2.0 file extension, and allows the build system to avoid linking files with debugging information. In order to be useful, this option requires a debugger capable of reading .dwo files, such as the version of GDB included in Red Hat Developer T oolset 2.0. Note elfutils, SystemT ap, and Valgrind do not support the .dwo files. B.2.1.4 . C++ Changes Experimental C++ Features from an Upcoming Standard g++ now supports a new command line option, -std=c++1y. T his option can be used for experimentation with features proposed for the next revision of the standard that is expected around 2014. Currently, the only difference from -std=c++11 is support for return type deduction in normal functions as proposed in N3386. New thread_local Keyword g++ now implements the C++11 thread_local keyword. In comparison with the GNU __thread keyword, thread_local allows dynamic initialization and destruction semantics. T he use of the thread_local keyword has currently one important limitation: when the dlclose() function is used to unload a dynamically loaded DSO that contains the definition of a thread_local object, the thread_local object is destroyed, its destructor is called and the DSO is unmapped from the address space of the process. If a thread in the process tries to access the thread_local object after this, the program may terminate unexpectedly. As a result, the programmer may have to take extra care to ensure that thread_local objects in a DSO are not referred after it has been unloaded. See also the next item for dynamic initialization issues. Dynamic Initialization of T hread-local Variables T he C++11 and OpenMP standards allow thread-local and thread-private variables to have dynamic (that is, runtime) initialization. T o support this, any use of such a variable goes through a wrapper function that performs necessary initialization. When the use and definition of the variable are in the same translation unit, this overhead can be optimized away, but when the use is in a different translation unit, there is significant overhead even if the variable does not actually need dynamic initialization. If the programmer can be sure that no use of the variable in a non-defining translation unit needs to trigger dynamic initialization (either because the variable is statically initialized, or a use of the variable in the defining translation unit will be executed before any uses in another translation unit), they can avoid this overhead by using the new -fnoextern-tls-init option. By default, g++ uses the -fextern-tls-init option. C++11 Attribute Syntax g++ now implements the C++11 attribute syntax, for example: [[noreturn]] void f(); 123 Red Hat D eveloper Toolset 2.x User Guide C++11 Alignment Specifier g++ now implements the C++11 alignment specifier, for example: alignas(double) int i; B.2.1.5. Fortran Changes B.2.1.5.1. Caveats T he version of module files (the .m od files) has been incremented. Fortran modules compiled by earlier GCC versions have to be recompiled when they are used by files compiled with GCC 4.8, as this version of GCC is not able to read .m od files created by earlier versions; attempting to do so fails with an error message. Note T he ABI of the produced assembler data itself has not changed; object files and libraries are fully compatible with older versions except as noted in Section B.2.1.5.2, “ABI Compatibility”. B.2.1.5.2. ABI Compatibility Some internal names used in the assembler or object file have changed for symbols declared in the specification part of a module. If an affected module — or a file using it via use association — is recompiled, the module and all files which directly use such symbols have to be recompiled as well. T his change only affects the following kind of module symbols: Procedure pointers. Note that C-interoperable function pointers (type(c_funptr)) are not affected, nor are procedure-pointer components. Deferred-length character strings. B.2.1.5.3. Other Changes BACKT RACE Intrinsic A new intrinsic subroutine, BACKT RACE, has been added. T his subroutine shows a backtrace at an arbitrary place in user code, program execution continues normally afterwards. Floating Point Numbers with “q” as Exponential Reading floating point numbers that use q for the exponential (such as 4 .0q0) is now supported as a vendor extension for better compatibility with old data files. It is strongly recommended to use the equivalent but standard conforming e (such as 4 .0e0) for I/O. For Fortran source code, consider replacing the q in floating-point literals by a kind parameter (such as 4 .0e0_qp with a suitable qp). Note that — in Fortran source code — replacing q with a simple e is not equivalent. GFORT RAN_T MPDIR Environment Variable T he GFORT RAN_T MPDIR environment variable for specifying a non-default directory for files opened with ST AT US="SCRAT CH", is not used anymore. Instead, gfortran checks the POSIX/GNU standard T MPDIR environment variable and if T MPDIR is not defined, gfortran falls back to other methods to determine the directory for temporary files as documented in the user manual. 124 Changes in Version 2.0 Fortran 2003 Support for unlimited polymorphic variables (CLASS(* )) has been added. Non-constant character lengths are not yet supported. T S 29113 Assumed types (T YPE(* )) are now supported. Experimental support for assumed-rank arrays (dim ension(..)) has been added. Note that at the moment, the gfortran array descriptor is used, which is different from the array descriptor defined in TS 29113. For more information, see the header file of gfortran or use the Chasm language interoperability tools. B.2.1.6. x86-specific Improvements New Instructions GCC 4.8 has added support for the Intel FXSR, XSAVE, and XSAVEOPT instructions. Corresponding intrinsics and built-in functions can now be enabled by using the -m fxsr, -m xsave, and -m xsaveopt command line options respectively. In addition, support for the RDSEED, ADCX, ADOX, and PREFET CHW instructions has been added and can be enabled by using the -m rdseed, -m adx, and -m prfchw command line options. New Built-in Functions to Detect Run-time CPU T ype and ISA A new built-in function, __builtin_cpu_is(), has been added to detect if the run-time CPU is of a particular type. T his function accepts one string literal argument with the CPU name, and returns a positive integer on a match and zero otherwise. For example, __builtin_cpu_is("westm ere") returns a positive integer if the run-time CPU is an Intel Core i7 Westmere processor. For a complete list of valid CPU names, see the user manual. A new built-in function, __builtin_cpu_supports(), has been added to detect if the run-time CPU supports a particular ISA feature. T his function accepts one string literal argument with the ISA feature, and returns a positive integer on a match and zero otherwise. For example, __builtin_cpu_supports("ssse3") returns a positive integer if the run-time CPU supports SSSE3 instructions. For a complete list of valid ISA names, see the user manual. Important If these built-in functions are called before any static constructors are invoked, such as IFUNC initialization, then the CPU detection initialization must be explicitly run using this newly provided built-in function, __builtin_cpu_init(). T he initialization needs to be done only once. For example, the following is sample invocation inside an IFUNC initializer: static void (*some_ifunc_resolver(void))(void) { __builtin_cpu_init(); if (__builtin_cpu_is("amdfam10h") ... if (__builtin_cpu_supports("popcnt") ... } 125 Red Hat D eveloper Toolset 2.x User Guide Function Multiversioning Function multiversioning allows the programmer to specify multiple versions of the same function, each of which is specialized for a particular variant of a given target. At runtime, the appropriate version is automatically executed depending upon the target where the execution takes place. For example, consider the following code fragment: __attribute__ ((target ("default"))) int foo () { return 0; } __attribute__ ((target ("sse4.2"))) int foo () { return 1; } __attribute__ ((target ("arch=atom"))) int foo () { return 2; } When the function foo() is executed, the result returned depends upon the architecture where the program runs, not the architecture where the program was compiled. See the GCC Wiki for more details. New RT M and HLE Intrinsics Support for the Intel RT M and HLE intrinsics, built-in functions, and code generation has been added and can be enabled by using the -m rtm and -m hle command line options. T his is done via intrinsics for Restricted Transactional Memory (RT M) and extensions to the memory model for Hardware Lock Elision (HLE). For HLE, two new flags can be used to mark a lock as using hardware elision: __AT OMIC_HLE_ACQUIRE Starts lock elision on a lock variable. T he memory model in use must be __AT OMIC_ACQUIRE or stronger. __AT OMIC_HLE_RELEASE Ends lock elision on a lock variable. T he memory model must be __AT OMIC_RELEASE or stronger. For example, consider the following code fragment: while (__atomic_exchange_n (& lockvar, 1, __ATOMIC_ACQUIRE | __ATOMIC_HLE_ACQUIRE)) _mm_pause (); // work with the acquired lock __atomic_clear (& lockvar, __ATOMIC_RELEASE | __ATOMIC_HLE_RELEASE); T he new intrinsics that support Restricted T ransactional Memory are: unsigned _xbegin (void) Attempts to start a transaction. If it succeeds, this function returns _XBEGIN_ST ART ED, otherwise it returns a status value indicating why the transaction could not be started. void _xend (void) Commits the current transaction. When no transaction is active, this function causes a fault. All memory side effects of the transactions become visible to other threads in an atomic manner. int _xtest (void) 126 Changes in Version 2.0 Returns a non-zero value if a transaction is currently active, or zero if it is not. void _xabort (unsigned char status) Aborts the current transaction. When no transaction is active, this is a no-op. T he parameter status is included in the return value of any _xbegin() call that is aborted by this function. T he following example illustrates the use of these intrinsics: if ((status = _xbegin ()) == _XBEGIN_STARTED) { // some code _xend (); } else { // examine the status to see why the transaction failed and possibly retry } T ransactions Using T ransactional Synchronization Extensions T ransactions in the transactional memory feature (the -fgnu-tm option) of GCC can now be run using Transactional Synchronization Extensions (T SX) if available on x86 hardware. Support for AMD Family 15h Processors T he x86 backend of GCC now supports CPUs based on AMD Family 15h cores with the 64-bit x86 instruction set support. T his can be enabled by using the -m arch=bdver3 option. Support for AMD Family 16h Processors T he x86 backend of GCC now supports CPUs based on AMD Family 16h cores with the 64-bit x86 instruction set support. T his can be enabled by using the -m arch=btver2 option. B.2.2. Changes Since Red Hat Enterprise Linux 6.4 and 5.9 T he following features have been added since the release of GCC included in Red Hat Enterprise Linux 6.4 and 5.9: B.2.2.1. Status and Features B.2.2.1.1. C++11 GCC 4.7 and later provides experimental support for building applications compliant with C++11 using the -std=c++11 or -std=gnu++11 command line options. However, there is no guarantee for compatibility between C++11 code compiled by different versions of the compiler. Refer to Section B.2.2.3.1, “C++ ABI” for details. T he C++ runtime library, libstdc++, supports a majority of the C++11 features. However, there is no or only partial support for some features such as certain properties on type traits or regular expressions. For details, refer to the libstdc++ documentation, which also lists implementationdefined behavior. Support for C++11 exception_ptr and future requires changes to the exception handling runtime in the system libstdc++ package. T hese changes will be distributed through the normal Z -stream channel. Application of all Red Hat Enterprise Linux errata may be required to see correct runtime functionality 127 Red Hat D eveloper Toolset 2.x User Guide when using these features. B.2.2.1.2. C11 GCC 4.7 and later provides experimental support for some of the features from the C11 revision of the ISO C standard, and in addition to the previous (now deprecated) -std=c1x and -std=gnu1x command line options, gcc now accepts -std=c11 and -std=gnu11. Note that since this support is experimental, it may change incompatibly in future releases. Examples for features that are supported are Unicode strings (including the predefined macros __ST DC_UT F_16__ and __ST DC_UT F_32__), nonreturning functions (_Noreturn and <stdnoreturn.h>), and alignment support (_Alignas, _Alignof, m ax_align_t, and <stdalign.h>). B.2.2.1.3. Parallelism and Concurrency GCC 4 .7 and later provides improved support for programming parallel applications: 1. T he GCC compilers support the OpenMP API specification for parallel programming, version 3.1. Refer to the OpenMP website for more information about this specification. 2. T he C++11 and C11 standards provide programming abstractions for multi-threaded programs. T he respective standard libraries include programming abstractions for threads and threadrelated features such as locks, condition variables, or futures. T hese new versions of the standard also define a memory model that precisely specifies the runtime behavior of a multithreaded program, such as the guarantees provided by compilers and the constraints programmers have to pay attention to when writing multi-threaded programs. Note that support for the memory model is still experimental (see below for details). For more information about the status of support for C++11 and C11, refer to Section B.2.2.1.1, “C++11” and Section B.2.2.1.2, “C11” respectively. T he rest of this section describes two new GCC features in more detail. Both these features make it easier for programmers to handle concurrency (such as when multiple threads do not run truly in parallel but instead have to synchronize concurrent access to shared state), and both provide atomicity for access to memory but differ in their scope, applicability, and complexity of runtime support. C++11 T ypes and GCC Built-ins for Atomic Memory Access C++11 has support for atomic types. Access to memory locations of this type is atomic, and appears as one indivisible access even when other threads access the same memory location concurrently. T he atomicity is limited to a single read or write access or one of the other atomic operations supported by such types (for example, two subsequent operations executed on a variable of atomic type are each atomic separately, but do not form one joint atomic operation). An atomic type is declared as atom ic<T>, where T is the non-atomic base type and must be trivially copyable (for example, atom ic<int> is an atomic integer). GCC does not yet support any base type T, but only those that can be accessed atomically with the atomic instructions offered by the target architecture. T his is not a significant limitation in practice, given that atomics are primarily designed to expose hardware primitives in an architecture-independent fashion; pointers and integrals that are not larger than a machine word on the target are supported as base types. Using base types that are not yet supported results in link-time errors. T he code generated for operations on atomic types, including the memory orders, implements the semantics specified in the C++11 standard. However, support for the C++11 memory model is still experimental, and for example GCC might not always preserve data-race freedom when optimizing code. GCC also supports new built-ins for atomic memory accesses, which follow the design of the memory model and new atomic operations. T he former set of synchronization built-ins (that is, those prefixed 128 Changes in Version 2.0 with __sync) are still supported. T ransactional Memory Transactional Memory (T M) allows programs to declare that a piece of code is supposed to execute as a transaction, that is, virtually atomically and in isolation from other transactions. GCC's transactional memory runtime library, libitm , then ensures this atomicity guarantee when executing the compiled program. Compared to atomic memory accesses, it is a higher-level programming abstraction, because it is not limited to single memory locations, does not require special data types for the data it modifies, and because transactions can contain arbitrary code and be nested within other transactions (with some restrictions explained subsequently). GCC implements transactions as specified in the Draft Specification for T ransactional Language Constructs for C++, version 1.1. T his draft does not yet specify the language constructs for C, but GCC already supports a C-compatible subset of the constructs when compiling C source code. T he main language constructs are transaction statements and expressions, and are declared by the __transaction_atom ic or __transaction_relaxed keywords followed by a compound statement or expression, respectively. T he following example illustrates how to increment a global variable y if another variable x has a value less than 10: __transaction_atomic { if (x < 10) y++; } T his happens atomically even in a multi-threaded execution of the program. In particular, even though the transaction can load x and y and store to y, all these memory accesses are virtually executed as one indivisible step. Note that in line with the C++11 memory model, programs that use transactions must be free of data races. T ransactions are guaranteed to be virtually executed serially in a global total order that is determined by the transactional memory implementation and that is consistent with and contributes to the happens-before order enforced by the rest of the program (that is, transaction semantics are specified based on the C++11 memory model, see the draft specification linked above). Nonetheless, if a program is not data-race-free, then it has undefined behavior. For example, a thread can first initialize some data and then make it publicly accessible by code like this: init(data); __transaction_atomic { data_public = true;} // data_public is initially false Another thread can then safely use the data, for instance: __transaction_atomic { if (data_public) use(data); } However, the following code has a data race and thus results in undefined behavior: __transaction_atomic { temp = copy(data); if (data_public) use(temp); } Here, copy(data) races with init(data) in the initializing thread, because this can be executed even if data_public is not true. Another example for data races is one thread accessing a variable x transactionally and another thread accessing it nontransactionally at potentially the same time. Note that the data can be safely reclaimed using code like this (assuming only one thread ever does this): __transaction_atomic { data_public = false; } destruct(data); 129 Red Hat D eveloper Toolset 2.x User Guide Here, destruct() does not race with potential concurrent uses of the data because after the transaction finishes, it is guaranteed that data_public is false and thus data is private. See the specification and the C++11 memory model for more background information about this. Note that even if transactions are required to virtually execute in a total order, this does not mean that they execute mutually exclusive in time. T ransactional memory implementations attempt to run transactions as much in parallel as possible to provide scalable performance. T here are two variants of transactions: atomic transactions (__transaction_atom ic) and relaxed transactions (__transaction_relaxed). T he former guarantee atomicity with regard to all other code, but allow only code that is known to not include nontransactional kinds of synchronization, such as atomic or volatile memory access. In contrast, relaxed transactions allow all code (for example calls to I/O functions), but only provide atomicity with regard to other transactions. T herefore, atomic transactions can be nested within other atomic and relaxed transactions, but relaxed transactions can only be nested within other relaxed transactions. Furthermore, relaxed transactions are likely to be executed with less performance, but this depends on the implementation and available hardware. GCC verifies these restrictions statically at compile time (for example, the requirements on code allowed to be called from within atomic transactions). T his has implications for when transactions call functions that are defined within other compilation unit (source file) or within libraries. T o enable such crosscompilation-unit calls for transactional code, the respective functions must be marked to contain code that is safe to use from within atomic transactions. Programmers can do so by adding the transaction_safe function attribute to the declarations of these functions and by including this declaration when defining the function. In turn, GCC then verifies that the code in these functions is safe for atomic transactions and generates code accordingly. If the programmer does not follow these constraints and/or steps, compile-time or link-time errors occur. Note that within a compilation unit, GCC detects automatically whether a function is safe for use within transactions, and the attributes therefore typically do not need to be added. See the draft specification linked above for further details. GCC's transactional memory support is designed in such a way that it does not decrease the performance of programs that do not use transactions, nor the performance of nontransactional code, except due to the normal kinds of interference by concurrent threads that use the same resources such as the CPU. T ransactional memory support in GCC and libitm is still experimental, and both the ABI and API could change in the future if this is required due to the evolution of the specification of the language constructs, or due to implementation requirements. Note that when executing applications built with the fgnu-tm command line option, it is currently a prerequisite to also have the appropriate version of the libitm .so.1 shared library installed. B.2.2.1.4 . Architecture-specific Options Red Hat Developer T oolset 2.0 is only available for Red Hat Enterprise Linux 5 and 6, both for the 32-bit and 64-bit Intel and AMD architectures. Consequently, the options described below are only relevant to these architectures. Optimization for several processors is now available through the command line options described in T able B.1, “Processor Optimization Options”. 130 Changes in Version 2.0 T able B.1. Processor Optimization Options Option Description -m arch=core2 and -m tune=core2 Optimization for Intel Core 2 processors. -m arch=corei7 and -m tune=corei7 Optimization for Intel Core i3, i5, and i7 processors. -m arch=corei7-avx and -m tune=corei7avx Optimization for Intel Core i3, i5, and i7 processors with AVX. -m arch=core-avx-i Optimization for the Intel processor code-named Ivy Bridge with RDRND, FSGSBASE, and F16C. -m arch=core-avx2 Optimization for a next-generation processor from Intel with AVX2, FMA, BMI, BMI2, and LZ CNT . -m arch=bdver2 and -m tune=bdver2 Optimization for AMD Opteron processors codenamed Piledriver. -m arch=btver1 and -m tune=btver1 Optimization for AMD family 14 processors codenamed Bobcat. -m arch=bdver1 and -m tune=bdver1 Optimization for AMD family 15h processors code-named Bulldozer. Support for various processor-specific intrinsics and instructions is now available through the command line options described in T able B.2, “Support for Processor-specific Intrinsics and Instructions”. T able B.2. Support for Processor-specific Intrinsics and Instructions Option Description -m avx2 Support for Intel AVX2 intrinsics, built-in functions, and code generation. -m bm i2 Support for Intel BMI2 intrinsics, built-in functions, and code generation. -m lzcnt Implementation and automatic generation of __builtin_clz* using the lzcnt instruction. -m fm a Support for Intel FMA3 intrinsics and code generation. -m fsgsbase Enables the generation of new segment register read/write instructions through dedicated built-ins. -m rdrnd Support for the Intel rdrnd instruction. -m f16c Support for two additional AVX vector conversion instructions. -m tbm Support for T BM (T railing Bit Manipulation) built-in functions and code generation. -m bm i Support for AMD's BMI (Bit Manipulation) built-in functions and code generation. -m crc32 Support for crc32 intrinsics. -m m ovbe Enables the use of the m ovbe instruction to implement __builtin_bswap32 and __builtin_bswap64 . -m xop, -m fm a4 , and m lwp Support for the XOP, FMA4, and LWP instruction sets for the AMD Orochi processors. -m abm Enables the use of the popcnt and lzcnt instructions on AMD processors. -m popcnt Enables the use of the popcnt instruction on both AMD and Intel processors. 131 Red Hat D eveloper Toolset 2.x User Guide When using the x87 floating-point unit, GCC now generates code that conforms to ISO C99 in terms of handling of floating-point excess precision. T his can be enabled by -fexcess-precision=standard and disabled by -fexcess-precision=fast. T his feature is enabled by default when using standards conformance options such as -std=c99. Vectors of type vector long long or vector long are passed and returned using the same method as other vectors with the VSX instruction set. Previously GCC did not adhere to the ABI for 128bit vectors with 64-bit integer base types (see GCC PR 48857). T he -m recip command line option has been added, which indicates whether the reciprocal and reciprocal square root instructions should be used. T he -m veclibabi=m ass command line option has been added. T his can be used to enable the compiler to auto-vectorize mathematical functions using the Mathematical Acceleration Subsystem library. T he -m single-pic-base command line option has been added, which instructs the compiler to avoid loading the PIC base register in function prologues. T he PIC base register must be initialized by the runtime system. T he -m block-m ove-inline-lim it command line option has been added, which enables the user to control the maximum size of inlined m em cpy calls and similar. B.2.2.1.5. Link-time Optimization Link-time optimization (LT O) is a compilation technique in which GCC generates an internal representation of each compiled input file in addition to the native code, and writes both to the output object file. Subsequently, when several object files are linked together, GCC uses the internal representations of the compiled code to optimize inter-procedurally across all the compilation units. T his can potentially improve the performance of the generated code (for example, functions defined in one file can potentially be inlined when called in another file). T o enable LT O, the -flto option needs to be specified at both compile time and link time. For further details, including interoperability with linkers and parallel execution of LT O, refer to the documentation for -flto in the GCC 4.7.0 Manual. Also note that the internal representation is not a stable interface, so LT O will only apply to code generated by the same version of GCC. Note Use of Link-time Optimization with debug generation is not yet supported in gcc 4.7 and 4.8 and so use of the -flto and the -g options together is unsupported in Red Hat Developer T oolset. B.2.2.1.6. Miscellaneous -Ofast is now supported as a general optimization level. It operates similar to -O3, adds options that can yield better-optimized code, but in turn might invalidate standards compliance (for example, -ffastm ath is enabled by -Ofast). GCC can now inform users about cases in which code generation might be improved by adding attributes such as const, pure, and noreturn to functions declared in header files. Use the Wsuggest-attribute=[const|pure|noreturn] command line option to enable this. Assembler code can now make use of a goto feature that allows for jumps to labels in C code. 132 Changes in Version 2.0 B.2.2.2. Language Compatibility In this section, we describe the compatibility between the Red Hat Developer T oolset compilers and the Red Hat Enterprise Linux system compilers at the programming-language level (for example, differences in the implementation of language standards such as C99, or changes to the warnings generated by Wall). Some of the changes are a result of bug fixing, and some old behaviors have been intentionally changed in order to support new standards, or relaxed in standards-conforming ways to facilitate compilation or runtime performance. Some of these changes are not visible to the naked eye and will not cause problems when updating from older versions. However, some of these changes are visible, and can cause grief to users porting to Red Hat Developer T oolset's version of GCC. T he following text attempts to identify major issues and suggests solutions. B.2.2.2.1. C Constant expressions are now handled by GCC in a way that conforms to C90 and C99. For code expressions that can be transformed into constants by the compiler but are in fact not constant expressions as defined by ISO C, this may cause warnings or errors. Ill-formed redeclarations of library functions are no longer accepted by the compiler. In particular, a function with a signature similar to the built-in declaration of a library function (for example, abort() or m em cpy()) must be declared with extern "C" to be considered as a redeclaration, otherwise it is illformed. Duplicate Member Consider the following struct declaration: struct A { int *a; union { struct { int *a; }; }; }; Previously, this declaration used to be diagnosed just by the C++ compiler, now it is also diagnosed by the C compiler. Because of the anonymous unions and structs, there is ambiguity about what .a actually refers to and one of the fields therefore needs to be renamed. B.2.2.2.2. C++ Header Dependency Changes <iostream >, <string>, and other ST L headers that previously included <unistd.h> as an implementation detail (to get some feature macros for gthr* .h purposes) no longer do so, because it was a C++ standard violation. T his can result in diagnostic output similar to the following: error: ‘truncate’ was not declared in this scope error: ‘sleep’ was not declared in this scope error: ‘pipe’ was not declared in this scope error: there are no arguments to 'offsetof' that depend on a template parameter, so a declaration of 'offsetof' must be available T o fix this, add the following line early in the source or header files that need it: #include <unistd.h> Many of the standard C++ library include files have been edited to no longer include <cstddef> to get namespace-std-scoped versions of size_t and ptrdiff_t. As such, C++ programs that used the 133 Red Hat D eveloper Toolset 2.x User Guide macros NULL or offsetof without including <cstddef> will no longer compile. T he diagnostic produced is similar to the following: error: 'ptrdiff_t' does not name a type error: 'size_t' has not been declared error: 'NULL' was not declared in this scope error: there are no arguments to 'offsetof' that depend on a template parameter, so a declaration of 'offsetof' must be available T o fix this issue, add the following line: #include <cstddef> Name Lookup Changes G++ no longer performs an extra unqualified lookup that it incorrectly performed in the past. Instead, it implements the two-phase lookup rules correctly, and an unqualified name used in a template must have an appropriate declaration that: 1. is either in scope at the point of the template's definition, or 2. can be found by argument-dependent lookup at the point of instantiation. Code that incorrectly depends on a second unqualified lookup at the point of instantiation (such as finding functions declared after the template or in dependent bases) will result in compile-time errors. In some cases, the diagnostics provided by G++ include hints how to fix the bugs. Consider the following code: template<typename T> int t(T i) { return f(i); } int f(int i) { return i; } int main() { return t(1); } T he following diagnostics output will be produced: In instantiation of ‘int t(T) [with T = int]’ required from here error: ‘f’ was not declared in this scope, and no declarations were found by argument-dependent lookup at the point of instantiation [-fpermissive] note: ‘int f(int)’ declared here, later in the translation unit T o correct the error in this example, move the declaration of function f() before the definition of template function t(). T he -fperm issive compiler flag turns compile-time errors into warnings and can be used as a temporary workaround. 134 Changes in Version 2.0 Uninitialized const Consider the following declaration: struct A { int a; A (); }; struct B : public A { }; const B b; An attempt to compile this code now fails with the following error: error: uninitialized const ‘b’ [-fpermissive] note: ‘const struct B’ has no user-provided default constructor T his happens, because B does not have a user-provided default constructor. Either an initializer needs to be provided, or the default constructor needs to be added. Visibility of T emplate Instantiations T he ELF symbol visibility of a template instantiation is now properly constrained by the visibility of its template arguments. For instance, users that instantiate standard library components like std::vector with hidden user defined types such as struct m y_hidden_struct can now expect hidden visibility for std::vector<m y_hidden_struct> symbols. As a result, users that compile with the fvisibility=hidden command line option should be aware of the visibility of types included from the library headers used. If the header does not explicitly control symbol visibility, types from those headers will be hidden, along with instantiations that use those types. For instance, consider the following code: #include <vector> // template std::vector has default visibility #include <ctime> // struct tm has hidden visibility template class std::vector<tm>; // instantiation has hidden visibility One approach to adjusting the visibility of a library header <foo.h> is to create a forwarding header on the -I include path consisting of the following: #pragma GCC visibility push(default) #include_next <foo.h> #pragma GCC visibility push User-defined Literal Support When compiling C++ with the -std={c++11,c++0x,gnu++11,gnu++0x} command line option, GCC 4.7.0 and later, unlike older versions, supports user-defined literals, which are incompatible with some valid ISO C++03 code. In particular, white space is now needed after a string literal before something that could be a valid user defined literal. Consider the following code: const char *p = "foobar"__TIME__; In C++03, the __T IME__ macro expands to some string literal and is concatenated with the other one. In C++11, __T IME__ is not expanded and instead, operator "" __T IME__ is being looked up, which results in a warning like: error: unable to find string literal operator ‘operator"" __TIME__’ T his applies to any string literal followed without white space by some macro. T o fix this, add some white space between the string literal and the macro name. 135 Red Hat D eveloper Toolset 2.x User Guide T aking the Address of T emporary Consider the following code: struct S { S (); int i; }; void bar (S *); void foo () { bar (&S ()); } Previously, an attempt to compile this code produced a warning message, now it fails with an error. T his can be fixed by adding a variable and passing the address of this variable instead of the temporary. T he -fperm issive compiler flag turns compile-time errors into warnings and can be used as a temporary workaround. Miscellaneous G++ now sets the predefined macro __cplusplus to the correct value: 199711L for C++98/03, and 201103L for C++11. G++ now properly re-uses stack space allocated for temporary objects when their lifetime ends, which can significantly lower stack consumption for some C++ functions. As a result of this, some code with undefined behavior will now break. When an extern declaration within a function does not match a declaration in the enclosing context, G++ now properly declares the name within the namespace of the function rather than the namespace which was open just before the function definition. G++ now implements the proposed resolution of the C++ standard's core issue 253. Default initialization is allowed if it initializes all subobjects, and code that fails to compile can be fixed by providing an initializer such as: struct A { A(); }; struct B : A { int i; }; const B b = B(); Access control is now applied to typedef names used in a template, which may cause G++ to reject some ill-formed code that was accepted by earlier releases. T he -fno-access-control option can be used as a temporary workaround until the code is corrected. G++ now implements the C++ standard's core issue 176. Previously, G++ did not support using the injected-class-name of a template base class as a type name, and lookup of the name found the declaration of the template in the enclosing scope. Now lookup of the name finds the injected-classname, which can be used either as a type or as a template, depending on whether or not the name is followed by a template argument list. As a result of this change, some code that was previously accepted may be ill-formed, because: 1. the injected-class-name is not accessible because it is from a private base, or 2. the injected-class-name cannot be used as an argument for a template parameter. In either of these cases, the code can be fixed by adding a nested-name-specifier to explicitly name the template. T he first can be worked around with -fno-access-control, the second is only rejected with -pedantic. B.2.2.2.3. C/C++ Warnings GCC 4.7.0 and later adds a number of new warnings that are either enabled by default, or by using the Wall option. Although these warnings do not result in a compilation failure on their own, often -Wall is 136 Changes in Version 2.0 used in conjunction with -Werror, causing these warnings to act like errors. T his section provides a list of these new or newly enabled warnings. Unless noted otherwise, these warnings apply to both C and C++. T he behavior of the -Wall command line option has changed and now includes the new warning flags Wunused-but-set-variable and, with -Wall -Wextra, -Wunused-but-set-param eter. T his may result in new warnings in code that compiled cleanly with previous versions of GCC. For example, consider the following code: void fn (void) { int foo; foo = bar (); } /* foo is never used. */ T he following diagnostic output will be produced: warning: variable "foo" set but not used [-Wunused-but-set-variable] T o fix this issue, first see if the unused variable or parameter can be removed without changing the result or logic of the surrounding code. If not, annotate it with __attribute__((__unused__)). As a workaround, you can use the -Wno-error=unused-but-set-variable or -Wno-error=unusedbut-set-param eter command line option. T he -Wenum -com pare option causes GCC to report a warning when values of different enum types are being compared. Previously, this option only worked for C++ programs, but now it works for C as well. T his warning is enabled by -Wall and may be avoided by using a type cast. Casting integers to larger pointer types now causes GCC to display a warning by default. T o disable these warnings, use the -Wno-int-to-pointer-cast option, which is available for both C and C++. Conversions between NULL and non-pointer types now cause GCC to report a warning by default. Previously, these warnings were only displayed when explicitly using -Wconversion. T o disable these warnings, use the new -Wno-conversion-null command line option. GCC can now warn when a class that has virtual functions and a non-virtual destructor is destroyed by using delete. T his is unsafe to do because the pointer might refer to a base class that does not have a virtual destructor. T he warning is enabled by -Wall and by a new command line option, -Wdeletenon-virtual-dtor. New -Wc++11-com pat and -Wc++0x-com pat options are now available. T hese options cause GCC to display a warning about C++ constructs whose meaning differs between ISO C++ 1998 and ISO C++ 2011 (such as identifiers in ISO C++ 1998 that are keywords in ISO C++ 2011). T his warning is enabled by -Wall and enables the -Wnarrowing option. B.2.2.2.4 . Fortran B.2.2.2.4 .1. New Features A new compile flag -fstack-arrays has been added. T his flag causes all local arrays to be put on stack memory, which can significantly improve the performance of some programs. Note that programs that use very large local arrays may require you to extend your runtime limits for stack memory. Compile time has been significantly improved. For example, the improvement may be noticeable when 137 Red Hat D eveloper Toolset 2.x User Guide working with programs that use large array constructors. T o improve code generation and diagnostics, the -fwhole-file compile flag is now enabled by default, and can be used with a newly supported -fwhole-program flag. T o disable it, use the deprecated -fno-whole-file flag. A new command line option -M is now supported. Similarly to gcc, this option allows you to generate Makefile dependencies. Note that the -cpp option may be required as well. T he -finit-real= command line option now supports snan as a valid value. T his allows you to initialize REAL and COMPLEX variables with a signaling NaN (not a number), and requires you to enable trapping (for example, by using the -ffpe-trap= command line option). Note that compiletime optimizations may turn a signaling NaN into a quiet NaN. A new command line option -fcheck= has been added. T his option accepts the following arguments: T he -fcheck=bounds option is equivalent to the -fbounds-check command line option. T he -fcheck=array-tem ps option is equivalent to the -fcheck-array-tem poraries command line option. T he -fcheck=do option checks for invalid modification of loop iteration variables. T he -fcheck=recursive option checks for recursive calls to subroutines or functions that are not marked as recursive. T he -fcheck=pointer option performs pointer association checks in calls, but does not handle undefined pointers nor pointers in expressions. T he -fcheck=all option enables all of the above options. A new command line option -fno-protect-parens has been added. T his option allows the compiler to reorder REAL and COMPLEX expressions with no regard to parentheses. When OpenMP's WORKSHARE is used, array assignments and WHERE will now be run in parallel. More Fortran 2003 and Fortran 2008 mathematical functions can now be used as initialization expressions. T he GCC$ compiler directive now enables support for some extended attributes such as ST DCALL. B.2.2.2.4 .2. Compatibility Changes T he -Ofast command line option now automatically enables the -fno-protect-parens and fstack-arrays flags. Front-end optimizations can now be disabled by the -fno-frontend-optim ize option, and selected by the -ffrontend-optim ize option. T he former is essentially only desirable if invalid Fortran source code needs to be compiled (for example, when functions—as compared to subroutines—have side-effects) or to work around compiler bugs. T he GFORT RAN_USE_ST DERR environment variable has been removed, and GNU Fortran now always prints error messages to standard error. T he -fdum p-core command line option and the GFORT RAN_ERROR_DUMPCORE environment variable have been removed. When encountering a serious error, GNU Fortran now always aborts the execution of the program. T he -fbacktrace command line option is now enabled by default. When a fatal error occurs, GNU Fortran now attempts to print a backtrace to standard error before aborting the execution of the program. T o disable this behavior, use the -fno-backtrace option. GNU Fortran no longer supports the use of the -M command line option to generate Makefile dependencies for the module path. T o perform this operation, use the -J option instead. T o significantly reduce the number of warnings, the -Wconversion command line option now only 138 Changes in Version 2.0 displays warnings when a conversion leads to information loss, and a new command line option Wconversion-extra has been added to display warnings about other conversions. T he Wconversion option is now enabled with -Wall. A new command line option -Wunused-dum m y-argum ent has been added. T his option can be used to display warnings about unused dummy arguments, and is now enabled with -Wall. Note that the -Wunused-variable option previously also warned about unused dummy arguments. T he COMMON default padding has been changed. Previously, the padding was added before a variable. Now it is added after a variable to increase the compatibility with other vendors, as well as to help to obtain the correct output in some cases. Note that this behavior is in contrast with the behavior of the -falign-com m ons option. GNU Fortran no longer links against the libgfortranbegin library. T he MAIN__ assembler symbol is the actual Fortran main program and is invoked by the m ain function, which is now generated and put in the same object file as MAIN__. Note that the libgfortranbegin library is still present for backward compatibility. B.2.2.2.4 .3. Fortran 2003 Features Improved but still experimental support for polymorphism between libraries and programs and for complicated inheritance patterns. Generic interface names which have the same name as derived types are now supported, which allows the creation of constructor functions. Note that Fortran does not support static constructor functions; only default initialization or an explicit structure-constructor initialization are available. Automatic (re)allocation: In intrinsic assignments to allocatable variables, the left-hand side will be automatically allocated (if unallocated) or reallocated (if the shape or type parameter is different). T o avoid the small performance penalty, you can use a(:) = ... instead of a = ... for arrays and character strings — or disable the feature using -std=f95 or -fno-realloc-lhs. Experimental support of the ASSOCIAT E construct has been added. In pointer assignments it is now possible to specify the lower bounds of the pointer and, for a rank-1 or a simply contiguous data-target, to remap the bounds. Deferred type parameter: For scalar allocatable and pointer variables the character length can now be deferred. Namelist variables with allocatable attribute, pointer attribute, and with a non-constant length type parameter are now supported. Support has been added for procedure-pointer function results and procedure-pointer components (including PASS). Support has been added for allocatable scalars (experimental), DEFERRED type-bound procedures, and the ERRMSG= argument of the ALLOCAT E and DEALLOCAT E statements. T he ALLOCAT E statement now supports type-specs and the SOURCE= argument. Rounding (ROUND=, RZ, ...) for output is now supported. T he INT _FAST {8,16,32,64 ,128}_T format for ISO_C_BINDING intrinsic module type parameters is now supported. OPERAT OR(* ) and ASSIGNMENT (=) are now allowed as GENERIC type-bound procedures (i.e. as type-bound operators). B.2.2.2.4 .4 . Fortran 2003 Compatibility Extensible derived types with type-bound procedure or procedure pointer with PASS attribute now have to use CLASS in line with the Fortran 2003 standard; the workaround to use T YPE is no longer supported. 139 Red Hat D eveloper Toolset 2.x User Guide B.2.2.2.4 .5. Fortran 2008 Features A new command line option -std=f2008ts has been added. T his option enables support for programs that conform to the Fortran 2008 standard and the draft T echnical Specification (T S) 29113 on Further Interoperability of Fortran with C. For more information, refer to the Chart of Fortran T S 29113 Features supported by GNU Fortran. T he DO CONCURRENT construct is now supported. T his construct can be used to specify that individual loop iterations do not have any interdependencies. Full single-image support except for polymorphic coarrays has been added, and can be enabled by using the -fcoarray=single command line option. Additionally, GNU Fortran now provides preliminary support for multiple images via an MPI-based coarray communication library. Note that the library version is not yet usable as remote coarray access is not yet possible. T he ST OP and ERROR ST OP statements have been updated to support all constant expressions. T he CONT IGUOUS attribute is now supported. Use of ALLOCAT E with the MOLD argument is now supported. T he ST ORAGE_SIZE intrinsic inquiry function is now supported. T he NORM2 and PARIT Y intrinsic functions are now supported. T he following bit intrinsics have been added: the POPCNT and POPPAR bit intrinsics for counting the number of 1 bits and returning the parity; the BGE, BGT , BLE, and BLT bit intrinsics for bitwise comparisons; the DSHIFT L and DSHIFT R bit intrinsics for combined left and right shifts; the MASKL and MASKR bit intrinsics for simple left and right justified masks; the MERGE_BIT S bit intrinsic for a bitwise merge using a mask; the SHIFT A, SHIFT L, and SHIFT R bit intrinsics for shift operations; the transformational bit intrinsics IALL, IANY, and IPARIT Y. T he EXECUT E_COMMAND_LINE intrinsic subroutine is now supported. T he IMPURE attribute for procedures is now supported. T his allows the use of ELEMENT AL procedures without the restrictions of PURE. Null pointers (including NULL()) and unallocated variables can now be used as an actual argument to optional non-pointer, non-allocatable dummy arguments, denoting an absent argument. Non-pointer variables with the T ARGET attribute can now be used as an actual argument to POINT ER dummies with INT ENT (IN). Pointers that include procedure pointers and those in a derived type (pointer components) can now also be initialized by a target instead of only by NULL. T he EXIT statement (with construct-name) can now be used to leave the ASSOCIAT E, BLOCK, IF, SELECT CASE, and SELECT T YPE constructs in addition to DO. Internal procedures can now be used as actual arguments. T he named constants INT EGER_KINDS, LOGICAL_KINDS, REAL_KINDS, and CHARACT ER_KINDS of the intrinsic module ISO_FORT RAN_ENV have been added. T hese arrays contain the supported 'kind' values for the respective types. T he C_SIZEOF module procedures of the ISO_C_BINDINGS intrinsic module and the COMPILER_VERSION and COMPILER_OPT IONS module procedures of the ISO_FORT RAN_ENV intrinsic module have been implemented. T he OPEN statement now supports the NEWUNIT = option. T his option returns a unique file unit and therefore prevents inadvertent use of the same unit in different parts of the program. Unlimited format items are now supported. 14 0 Changes in Version 2.0 T he INT {8,16,32} and REAL{32,64 ,128} format for ISO_FORT RAN_ENV intrinsic module type parameters are now supported. It is now possible to use complex arguments with the T AN, SINH, COSH, T ANH, ASIN, ACOS, and AT AN functions. Additionally, the new functions ASINH, ACOSH, and AT ANH have been added for real and complex arguments, and AT AN(Y,X) now serves as an alias for AT AN2(Y,X). T he BLOCK construct has been implemented. B.2.2.2.4 .6. Fortran 2008 Compatibility T he implementation of the ASYNCHRONOUS attribute in GCC is now compatible with the candidate draft of TS 29113: Technical Specification on Further Interoperability with C. B.2.2.2.4 .7. Fortran 77 Compatibility When the GNU Fortran compiler is issued with the -fno-sign-zero option, the SIGN intrinsic now behaves as if zero were always positive. B.2.2.3. ABI Compatibility T his section describes compatibility between the Red Hat Developer T oolset compilers and the system compilers at the application binary interface (ABI) level. B.2.2.3.1. C++ ABI Because the upstream GCC community development does not guarantee C++11 ABI compatibility across major versions of GCC, the same applies to use of C++11 with Red Hat Developer T oolset. Consequently, using the -std=c++11 option is supported in Red Hat Developer T oolset 2.0 only when all C++ objects compiled with that flag have been built using the same major version of Red Hat Developer T oolset. T he mixing of objects, binaries and libraries, built by the Red Hat Enterprise Linux 5 or 6 system toolchain GCC using the -std=c++0x or -std=gnu++0x flags, with those built with the std=c++11 or -std=gnu++11 flags using the GCC in Red Hat Developer T oolset is explicitly not supported. As later major versions of Red Hat Developer T oolset may use a later major release of GCC, forwardcompatibility of objects, binaries, and libraries built with the -std=c++11 or -std=gnu++11 options cannot be guaranteed, and so is not supported. T he default language standard setting for Red Hat Developer T oolset is C++98. Any C++98-compliant binaries or libraries built in this default mode (or explicitly with -std=c++98) can be freely mixed with binaries and shared libraries built by the Red Hat Enterprise Linux 5 or 6 system toolchain GCC. Red Hat recommends use of this default -std=c++98 mode for production software development. Important Use of C++11 features in your application requires careful consideration of the above ABI compatibility information. Aside from the C++11 ABI, discussed above, the Red Hat Enterprise Linux Application Compatibility Specification is unchanged for Red Hat Developer T oolset. When mixing objects built with Red Hat Developer T oolset with those built with the Red Hat Enterprise Linux v5.x/v6.x toolchain (particularly .o/.a files), the Red Hat Developer T oolset toolchain should be used for any linkage. T his ensures any newer library features provided only by Red Hat Developer T oolset are resolved at link-time. A new standard mangling for SIMD vector types has been added to avoid name clashes on systems with 14 1 Red Hat D eveloper Toolset 2.x User Guide vectors of varying length. By default the compiler still uses the old mangling, but emits aliases with the new mangling on targets that support strong aliases. -Wabi will now display a warning about code that uses the old mangling. B.2.2.3.2. Miscellaneous GCC now optimizes calls to various standard C string functions such as strlen(), strchr(), strcpy(), strcat() and stpcpy() (as well as their respective _FORT IFY_SOURCE variants) by transforming them into custom, faster code. T his means that there might be fewer or other calls to those functions than in the original source code. T he optimization is enabled by default at -O2 or higher optimization levels. It is disabled when using -fno-optim ize-strlen or when optimizing for size. When compiling for 32-bit GNU/Linux and not optimizing for size, -fom it-fram e-pointer is now enabled by default. T he prior default setting can be chosen by using the -fno-om it-fram e-pointer command line option. Floating-point calculations on x86 targets and in strict C99 mode are now compiled by GCC with a stricter standard conformance. T his might result in those calculations executing significantly slower. It can be disabled using -fexcess-precision=fast. B.2.2.4 . Debugging Compatibility GCC now generates DWARF debugging information that uses more or newer DWARF features than previously. GDB contained in Red Hat Developer T oolset can handle these features, but versions of GDB older than 7.0 cannot. GCC can be restricted to only generate debugging information with older DWARF features by using the -gdwarf-2 -gstrict-dwarf or -gdwarf-3 -gstrict-dwarf options (the latter are handled partially by versions of GDB older than 7.0). Many tools such as Valgrind, SystemT ap, or third-party debuggers utilize debugging information. It is suggested to use the -gdwarf-2 -gstrict-dwarf options with those tools. Note Use of Link-time Optimization with debug generation is not yet supported in gcc 4.7 and 4.8 and so use of the -flto and the -g options together is unsupported in Red Hat Developer T oolset. B.2.2.5. Other Compatibility GCC is now more strict when parsing command line options, and both gcc and g++ report an error when invalid command line options are used. In particular, when only linking and not compiling code, earlier versions of GCC ignored all options starting with --. For example, options accepted by the linker such as --as-needed and --export-dynam ic are not accepted by gcc and g++ anymore, and should now be directed to the linker using -Wl,--as-needed or -Wl,--export-dynam ic if that is intended. Because of the new link-time optimization feature (see Section B.2.2.1.5, “Link-time Optimization”), support for the older intermodule optimization framework has been removed and the -com bine command line option is not accepted anymore. B.3. Changes in binutils Red Hat Developer T oolset 2.0 is distributed with binutils 2.23.52, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version 14 2 Changes in Version 2.0 included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of new features in this release. T he GNU assembler (as), GNU linker (ld), and other binary tools that are part of binutils are now released under the GNU General Public License, version 3. B.3.1. GNU Linker Another ELF linker, gold, is now available in addition to ld, the existing GNU linker. gold is intended to be a drop-in replacement for ld, so ld's documentation is intended to be the reference documentation. gold supports most of ld's features, except notable ones such as MRI-compatible linker scripts, crossreference reports (--cref), and various other minor options. It also provides significantly improved link time with very large C++ applications. In Red Hat Developer T oolset 2.0, the gold linker is not enabled by default. Users can explicitly switch between ld and gold by using the alternatives mechanism. B.3.1.1. New Features Changes Since Red Hat Enterprise Linux 6.4 T he following features have been added since the release of binutils included in Red Hat Enterprise Linux 6.4: A new INPUT _SECT ION_FLAGS keyword has been added to the linker script language. T his keyword can be used to select input sections by section header flags. A new SORT _BY_INIT _PRIORIT Y keyword has been added to the linker script language. T his keyword can be used to sort sections by numerical value of the GCC init_priority attribute encoded in the section name. A new SORT _NONE keyword has been added to the linker script language. T his keyword can be used to disable section sorting. A new linker-provided symbol, __ehdr_start, has been added. When producing ELF output, this symbol points to the ELF file header (and nearby program headers) in the program's memory image. Changes Since Red Hat Enterprise Linux 5.9 T he following features have been added since the release of binutils included in Red Hat Enterprise Linux 5.9: GNU/Linux targets now support the ST B_GNU_UNIQUE symbol binding, a GNU extension to the standard set of ELF symbol bindings. T he binding is passed on to the dynamic linker, which ensures that in the entire process there is only one symbol with the given name and type in use. Note T he implementation of this feature depends on capabilities only found in newer versions of the glibc library. Consequently, this feature is currently available in Red Hat Developer T oolset for Red Hat Enterprise Linux 6. A new command line option --no-export-dynam ic has been added. T his option can be used to undo the effect of the -E and --export-dynam ic options. A new command line option --warn-alternate-em has been added. T his option can be used to display a warning if an ELF format object file uses an alternate machine code. A new linker script function REGION_ALIAS has been added. T his function can be used to create 14 3 Red Hat D eveloper Toolset 2.x User Guide alias names of memory regions. A new command line option -T text-segm ent address has been added for ELF-based targets. T his option can be used to set the address of the first byte of the text segment. A new linker script command INSERT has been added. T his command can be used to augment the default script. In a linker script input section, it is now possible to specify a file within an archive by using the archive:file syntax. T he --sort-com m on command line option now accepts ascending and descending as optional arguments. T his can be used to specify which sorting order to use. A new command line option --build-id has been added for ELF-based targets. T his option can be used to generate a unique per-binary identifier embedded in a note section. A new command line option --default-script=file_name (or -dT file_name) has been added. T his option can be used to specify a replacement for the built-in linker script. A new command line option -Bsym bolic-functions has been added. When creating a shared library, this option will cause references to global function symbols to be bound to the definitions with the shared library, if such exist. T he new command line options --dynam ic-list-cpp-new and --dynam ic-list-data have been added, which can be used to modify the dynamic list. B.3.1.2. Compatibility Changes Changes Since Red Hat Enterprise Linux 6.4 T he following compatibility changes have been made since the release of binutils included in Red Hat Enterprise Linux 6.4: T he --copy-dt-needed-entries command line option is no longer enabled by default. Instead, -no-copy-dt-needed-entries is now the default option. Evaluation of linker script expressions has been significantly improved. Note that this can negatively affect scripts that rely on undocumented behavior of the old expression evaluation. Changes Since Red Hat Enterprise Linux 5.9 T he following compatibility changes have been made since the release of binutils included in Red Hat Enterprise Linux 5.9: T he --add-needed command line option has been renamed to --copy-dt-needed-entries in order to avoid confusion with the --as-needed option. For GNU/Linux systems, the linker no longer processes any relocations made against symbols of the ST T _GNU_IFUNC type. Instead, it emits them into the resulting binary for processing by the loader. Note T he implementation of this feature depends on capabilities only found in newer versions of the glibc library. Consequently, this feature is currently available in Red Hat Developer T oolset for Red Hat Enterprise Linux 6. T he --as-needed command line option has been adapted to link in a dynamic library in the following two cases: 1. if the dynamic library satisfies undefined symbols in regular objects, and 2. if the dynamic library satisfies undefined symbols in other dynamic libraries unless the library 14 4 Changes in Version 2.0 is already found in a DT _NEEDED entry of one of the libraries that are already linked. T he -l:file_name command line option now searches the library path for a file name called file_name without adding the .a or .so file extension. B.3.2. GNU Assembler B.3.2.1. New Features Changes Since Red Hat Enterprise Linux 6.4 T he following features have been added since the release of binutils included in Red Hat Enterprise Linux 6.4: T he GNU Assembler no longer requires double ampersands in macros. A new --com press-debug-sections command line option has been added to enable compression of DWARF debug information sections in the relocatable output file. Compressed debug sections are currently supported by the readelf, objdum p, and gold tools, but not by ld. Support for .bundle_align_m ode, .bundle_lock, and .bundle_unlock directives for x86 targets has been added.. On x86 architectures, the GNU Assembler now allows rep bsf, rep bsr, and rep ret syntax. Changes Since Red Hat Enterprise Linux 5.9 T he following features have been added since the release of binutils included in Red Hat Enterprise Linux 5.9: GNU/Linux targets now support gnu_unique_object as a value of the .type pseudo operation. T his value can be used to mark a symbol as globally unique in the entire process. Support for the new discriminator column in the DWARF line table with a discriminator operand for the .loc directive has been added. T he .type pseudo operation now accepts a type of ST T _GNU_IFUNC. T his can be used to indicate that if the symbol is the target of a relocation, its value should not be used. Instead, the function should be invoked and its result used as the value. A new pseudo operation .cfi_val_encoded_addr has been added. T his pseudo operation can be used to record constant addresses in unwind tables without runtime relocation. A new command line option -m sse-check=[none|error|warning] has been added for x86 targets. T he -a command line option now accepts g as a valid sub-option. T his combination can be used to enable assembly listings with additional information about the assembly, including the list of supplied command line options or the assembler version. A new command line option -m sse2avx has been added for x86 targets. T his option can be used to encode SSE instructions with VEX prefix. x86 targets now support the Intel XSAVE, EPT , MOVBE, AES, PCLMUL, and AVX/FMA instructions. New command line options -m arch=cpu[,+extension… ], -m tune=cpu, m m nem onic=[att|intel], -m syntax=[att|intel], -m index-reg, -m naked-reg, and m old-gcc have been added for x86 targets. New pseudo operations .string16, .string32, and .string64 have been added. T hese pseudo operations be used to generate wide character strings. T he i386 port now supports the SSE5 instruction set. A new pseudo operation .reloc has been added. T his pseudo operation serves as a low-level 14 5 Red Hat D eveloper Toolset 2.x User Guide interface for creating relocations. B.3.3. Other Binary Tools B.3.3.1. New Features Changes Since Red Hat Developer T oolset 1.1 T he following features have been added since the release of binutils included in Red Hat Developer T oolset 1.1: A manual page for the dwp utility has been added. T he binary tools now provide support for the AMD Family 15h processors, models 02h and 10-1fh. Changes Since Red Hat Enterprise Linux 6.4 T he following features have been added since the release of binutils included in Red Hat Enterprise Linux 6.4: T he readelf and objdum p tools can now display the contents of the .debug.m acro sections. New --dwarf-start and --dwarf-end command line options have been added to the readelf and objdum p tools. T hese options are used by the new Emacs mode (see the dwarf-m ode.el file). A new --interleave-width command line option has been added to the objcopy tool to allow the use of the --interleave to copy a range of bytes from the input to the output. A new --dyn-sym s command line option has been added to the readelf tool. T his option can be used to dump dynamic symbol table. A new tool, elfedit, has been added to binutils. T his tool can be used to directly manipulate ELF format binaries. A new command line option --addresses (or -a for short) has been added to the addr2line tool. T his option can be used to display addresses before function and source file names. A new command line option --pretty-print (or -p for short) has been added to the addr2line tool. T his option can be used to produce human-readable output. Support for dwz -m optimized debug information has been added. T he devtoolset-2-binutils-devel package now provides the dem angle.h header file. Changes Since Red Hat Enterprise Linux 5.9 T he following features have been added since the release of binutils included in Red Hat Enterprise Linux 5.9: A new command line option --insn-width=width has been added to the objdum p tool. T his option can be used to specify the number of bytes to be displayed on a single line when disassembling instructions. A new command line option --relocated-dum p=name|number has been added to the readelf tool. T his option can be used to display the relocated contents of a section as a sequence of bytes. A new command line option --external-sym bols-table=filename has been added to the gprof tool. T his option can be used to read a symbol table from a certain file. bfd now supports a plugin target, which can be used to get basic support for new file formats by having the plugin target load the same shared objects used by gold. T he --dwarf (or -W for short) command line option of the objdum p tool has been adapted to be as flexible as the --debug-dum p (or -w) option of readelf. 14 6 Changes in Version 2.0 New command line options --prefix=prefix and --prefix-strip=level have been added to the objdum p tool. T hese options can be used to add absolute paths for the --source (or -S for short) option. A new command line option -wL has been added to the readelf tool. T his option can be used to dump decoded contents of the .debug_line section. “T hin” archives are now supported. Instead of containing object files, such archives contain just pathnames pointing to those files. A new command line option -F has been added to the objdum p tool. T his option can be used to include file offsets in the disassembly. A new command line option -c has been added to the readelf tool. T his option can be used to allow string dumps of archive symbol index. T he i386 port now supports the SSE5 instruction set. A new command line option -p has been added to the readelf tool. T his option can be used to allow string dumps of sections. B.3.3.2. Compatibility Changes Changes Since Red Hat Enterprise Linux 5.9 T he following compatibility changes have been made since the release of binutils included in Red Hat Enterprise Linux 5.9: T he --as-needed command line option has been adapted to link in a dynamic library in the following two cases: 1. if the dynamic library satisfies undefined symbols in regular objects, and 2. if the dynamic library satisfies undefined symbols in other dynamic libraries unless the library is already found in a DT _NEEDED entry of one of the libraries that are already linked. B.4. Changes in elfutils Red Hat Developer T oolset 2.0 is distributed with elfutils 0.155, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of new features in this release. B.4.1. Changes Since Red Hat Developer Toolset 1.1 T he following features have been added since the release of elfutils included in Red Hat Developer T oolset 1.1: In the libdw library, the DW_LANG_Objc constant has been correctly renamed to DW_LANG_ObjC. Note that any existing source code that uses the old name needs to be updated accordingly. T he libdw library now supports new constants DW_AT E_UT F and DW_OP_GNU_param eter_ref. In addition, it also defines a family of constants to support the .debug_m acro section, namely DW_MACRO_GNU_define, DW_MACRO_GNU_undef, DW_MACRO_GNU_start_file, DW_MACRO_GNU_end_file, DW_MACRO_GNU_define_indirect, DW_MACRO_GNU_undef_indirect, and DW_MACRO_GNU_transparent_include. When working with the libelf library, both elf32_xlatetom d and elf64 _xlatetom d now work for cross-endian ELF note data. T he elf_getshdr() function provided by the libelf library has been corrected to work consistently on non-mmapped ELF files after making the elf_cntl(ELF_C_FDREAD) function call. T he libelf library now supports ar archives with a 64-bit symbol table. 14 7 Red Hat D eveloper Toolset 2.x User Guide T he eu-readelf command is now able to display the contents of the .debug_m acro section. T he eu-readelf command now correctly recognizes the DW_OP_GNU_param eter_ref DWARF GNU extension opcode in location expressions. B.4.2. Changes Since Red Hat Enterprise Linux 6.4 T he following features have been added since the release of elfutils included in Red Hat Enterprise Linux 6.4: T he libdw library now handles compressed debuginfo sections. T he dwarf_highpc() function now handles the DWARF 4 DW_AT _high_pc constant form. T he eu-elflint utility now accepts executables produced by the gold linker. T he eu-nm utility now supports C++ demangling. T he eu-ar utility now supports a new modifier D for deterministic output with no UID, GID, or mtime info. T he U modifier is the inverse. T he eu-readelf utility can now print SDT ELF notes (SystemTap probes) and the .gdb_index GDB section. It can now also print DW_OP_GNU_entry_value and DW_AT _GNU_call_site families of DIE attributes. T he eu-strip utility now recognizes a new command line option, --reloc-debug-sections. B.4.3. Changes Since Red Hat Enterprise Linux 5.9 In addition to the above changes, the following features have been added since the release of elfutils included in Red Hat Enterprise Linux 5.9: DWARF 4 is now supported. As well, support for DW_OP_GNU_im plicit_pointer and ST B_GNU_UNIQUE has been added. T he libdwfl library now supports automatic decompression of files compressed with gzip, bzip2 and lzm a, and of Linux kernel images made with gzip, bzip2 or lzm a. Files named with compression suffixes are searched for Linux kernel images. Core file support was improved. Support has been added for decoding DWARF CFI into location description form. Support has been added for some new DWARF 3 expression operations, which were previously omitted. A new function, dwfl_dwarf_line(), has been added. T he eu-elfcm p utility now supports a new command line option --ignore-build-id to ignore differing build ID bits. T he new option --verbose (or -l for short) prints all differences. T he eu-strip utility now recognizes a new command line option --strip-sections to remove section headers entirely. T he libdw library now has new functions dwarf_next_unit(), dwarf_offdie_types(), dwarf_lineisa(), dwarf_linediscrim inator(), dwarf_lineop_index(), dwarf_getlocation_im plicit_pointer(), and dwarf_aggregate_size(). T he eu-addr2line utility now recognizes a new command line option --flags (or -F for short) to print more DWARF line information details. T he libelf library now supports using more than 65536 program headers in a file. In addition, a new function elf_getphdrnum () has been added. T he eu-addr2line utility now accepts the --section=name option (or -j name for short) in the interests of binutils compatibility. libcpu Intel SSE4 disassembler support has been added. T he eu-readelf utility now implements call frame information and exception handling dumping. T he -e command line option has been added; this is enabled implicitly by -a. 14 8 Changes in Version 2.0 B.5. Changes in dwz Red Hat Developer T oolset 2.0 is distributed with dwz 0.11, which provides a number of bug fixes and enhancements over the version included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of changes in this release. B.5.1. Changes Since Red Hat Developer Toolset 1.1 T he following features have been added since the release of dwz included in Red Hat Developer T oolset 1.1: T he DW_FORM_data4 , DW_FORM_data8, and DW_AT _high_pc attributes have been optimized. T he dwz utility now allocates more memory when recomputing abbreviations and no longer terminates unexpectedly. T he dwz utility no longer crashes when processing debugging information that contains several copies of the same Debugging Information Entry (DIE) within the same compilation unit. T he dwz utility no longer writes an incorrect DW_FORM code for a compilation unit version. T he dwz utility now supports version 8 of the .gdb_index section. B.6. Changes in GDB Red Hat Developer T oolset 2.0 is distributed with GDB 7.6, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of new features in this release. B.6.1. Changes Since Red Hat Developer Toolset 1.1 T he following features have been added since the release of GDB included in Red Hat Developer T oolset 1.1: T arget record has been renamed to record-full. Consequently, you can now use the record full command to record or replay an execution log. In addition, the following commands have been renamed: T he set record insn-num ber-m ax and show record insn-num ber-m ax commands have been renamed to set record full insn-num ber-m ax and show record full insn-num ber-m ax. T he set record m em ory-query and show record m em ory-query commands have been renamed to set record full m em ory-query and show record full m em ory-query. T he set record stop-at-lim it and show record stop-at-lim it commands have been renamed to set record full stop-at-lim it and show record full stop-atlim it. A new record target, record-btrace, has been added. T his target uses hardware support to record the control flow of a process and can be enabled by using the record btrace command. T his record target does not support replaying the execution. Important T he record-btrace target is only available on Intel Atom processors and requires the Linux kernel in version 2.6.32 or later. 14 9 Red Hat D eveloper Toolset 2.x User Guide New record instruction-history and record function-call-history commands have been added. T hese commands allow you to view information about an execution log without having to replay it. T he record instruction-history command displays the execution history at instruction granularity and the record function-call-history displays the execution history at function granularity. T he commands are only supported by the record btrace command. A new command line option, -nh, has been added. T his option allows you to disable automatic loading of the ~/.gdbinit file without disabling other initialization files. T he -epoch command line option has been removed. T his option was used by GDB mode in Epoch, a deprecated clone of the Emacs text editor. T he ptype and whatis commands have been updated to accept an argument to control the type formatting. T he info proc command has been updated to work on some core files. T he cd command has been enhanced and no longer requires a directory path as its first argument. When executed with no arguments, the command now changes to the home directory. GDB now uses GNU v3 ABI as the default C++ ABI. T his has been the default option for GCC since November 2000. T he info tracepoints command has been enhanced to display installed on target or not installed on target for each non-pending location of a tracepoint. A new command, fo, has been added. T his commands serves as a shorter variant of the forwardsearch command. A new command, catch signal, has been added. T his command can be used to catch signals by their names and is similar to the handle command, but also allows you to attach additional conditions or commands. A new command, m aint info bfds, has been added. T his command can be used to list all binary files (BFDs) opened by GDB. T wo new commands, python-interactive [command] and its shorter variant pi [command], have been added. T hese commands allow you to start an interactive Python prompt or evaluate a Python command and print the results to standard output. A new command, py [command], has been added. T his command serves as a shorter variant of the python [command] command. New enable type-printer [name...] and disable type-printer [name...] commands have been added. T hese commands allow you to enable or disable type printers. New set print type m ethods on|off and show print type m ethods commands have been added. T hese commands allow you to control whether method declarations are displayed by the ptype command. T his functionality is enabled by default. New set print type typedefs on|off and show print type typedefs commands have been added. T hese commands allow you to control whether typedef definitions are displayed by the ptype command. T his functionality is enabled by default. New set filenam e-display basenam e|relative|absolute and show filenam edisplay commands have been added. T hese commands allow you to control the way in which file names are displayed: the basenam e option displays only the base name of a file name, relative displays a path relative to the compilation directory, and absolute displays an absolute path to the file. T he default option is relative to preserve the previous behavior. New set trace-buffer-size and show trace-buffer-size commands have been added. T hese commands allow you to control the size of the trace buffer for a target. New set rem ote trace-buffer-size-packet auto|on|off and show rem ote tracebuffer-size-packet commands have been added. T hese commands allow you to control the 150 Changes in Version 2.0 use of the remote protocol QT Buffer:size packet. New set debug notification and show debug notification commands have been added. T hese commands allow you to control whether to display debugging information for asynchronous remote notification. T his functionality is disabled by default. New convenience functions $_m em eq(buf1, buf2, length), $_streq(str1, str2), $_strlen(str), and $_regex(str, regex) have been added. T he following changes have been made to the Python scripting support since the release of GDB included in Red Hat Developer T oolset 1.1: Users can now create vectors by using the gdb.T ype.vector() method. T he atexit.register() method is now supported. Users can now pretty-print types by using the Python API. In addition to Python 2.4 and later, GDB now also supports Python 3. A new class, gdb.Architecture, has been added. T his class exposes the internal representation of the architecture in the Python API. A new method, Fram e.architecture, has been added. T his method can be used to return the gdb.Architecture object corresponding to the frame's architecture. Frame filters and frame decorators have been added. T he following MI changes have been made since the release of GDB included in Red Hat Developer T oolset 1.1: A new async record, =cm d-param -changed, has been added. T his async record reports that a command parameter has changed. A new async record, =tracefram e-changed, has been added. T his async record reports that a trace frame has been changed by using the tfind command. New async records =tsv-created, =tsv-deleted, and =tsv-m odified have been added. T hese async records report that a trace state variable has been created, deleted, or modified. New async records =record-started and =record-stopped have been added. T hese async records report that a process record has been started or stopped. A new async record, =m em ory-changed, has been added. T his async record reports that the memory has changed. When the source is requested, the -data-disassem ble command now includes a new fullnam e field containing an absolute path to the source file name. A new optional parameter, COUNT , has been added to the -data-write-m em ory-bytes command. T his parameter can be used to allow pattern filling of memory areas. New commands -catch-load and -catch-unload have been added. T hese commands can be used to intercept shared library load/unload events. T he response to breakpoint commands and breakpoint async records now includes a new installed field. T his field reports the current state of each non-pending tracepoint location: when the tracepoint is installed, the value of this field is y, otherwise the value is n. T he output of the -trace-status command now includes a new trace-file field. T his field is only present when examining a trace file and contains the name of this file. T he fullnam e filed is now always present along with the file field. T his field is included even if GDB cannot find the file. A number of new remote packets have been added since the release of GDB included in Red Hat Developer T oolset 1.1. See T able B.3, “New Remote Packets” for a complete list. 151 Red Hat D eveloper Toolset 2.x User Guide T able B.3. New Remote Packets Remote Packet Description QT Buffer:size Sets the size of the trace buffer. T he remote stub reports support for this packet to the qSupported query. Qbtrace:bts Enables branch tracing based on Branch Trace Store (BT S) for the current thread. T he remote stub reports support for this packet to the qSupported query. Qbtrace:off Disables branch tracing for the current thread. T he remote stub reports support for this packet to the qSupported query. qXfer:btrace:read Reads the traced branches for the current thread. T he remote stub reports support for this packet to the qSupported query. qXfer:librariessvr4 :read's annex T he previously unused annex of the qXfer:librariessvr4 :read packet is now used to support passing of an argument list. T he remote stub reports support for this argument list to the qSupported query. T he defined arguments are start and prev. T hese arguments are used to reduce work necessary for updating the library list and significantly speed up the process. B.6.2. Changes Since Red Hat Enterprise Linux 6.4 T he features below have been added since the release of GDB included in Red Hat Enterprise Linux 6.4. New Features Support for linespecs has been improved (in particular, a more consistent handling of ambiguous linespecs, some support for labels in the program's source, and FILE:LINE support now extends to further linespecs types). Breakpoints are now set on all matching locations in all inferiors and will be updated according to changes in the inferior. New inferior control commands skip function and skip file have been added. T hese commands can be uses to skip certain functions and files when stepping. T he info threads command now displays the thread name as set by prctl or pthread_setnam e_np. In addition, new commands thread nam e and thread find have been added. T he thread nam e command accepts a name as an argument and can be used to set the name of the current thread. T he thread find command accepts a regular expression and allows the user to find threads that match it. GDB now provides support for reading and writing a new .gdb_index section. T he command gdbadd-index can be used to add .gdb_index to a file, which allows GDB to load symbols from that file faster. Note that this feature is already present in Red Hat Enterprise Linux 6.1 and later. T he watch command has been adapted to accept -location as an optional argument. T wo new special values can now be used when specifying the current search path for libthread_db: $sdir represents the default system locations of shared libraries, and $pdir stands for the directory with the libthread that is used by the application. A new command info m acros has been added. T his command accepts linespec as an optional argument and can be used to display the definitions of macros at that linespec location. Note that in order to do this, the debugged program must be compiled with the -g3 command line option to have 152 Changes in Version 2.0 macro information available in it. A new command alias has been added. T his command can be used to create an alias of an existing command. T he info m acro command now accepts -all and -- as valid options. T o display a function parameter's entry value (that is, the value at the time of function entry), the suffix @ entry can be added to the parameter. GDB now displays @ entry values in backtraces, if available. New set print entry-values and show print entry-values commands have been added. T he set print entry-values command accepts both, com pact, default, if-needed, no, only, and preferred as valid arguments and can be used to enable printing of function arguments at function entry. T he show print entry-values command can be used to determine whether this feature is enabled. New set debug entry-values and show debug entry-values commands have been added. T he set debug entry-values command can be used to enable printing of debugging information for determining frame argument values at function entry and virtual tail call frames. !command has been added as an alias of shell command. T he watch command now accepts m ask mask_value as an argument. T his can be used to create masked watchpoints. New set extended-prom pt and show extended-prom pt commands have been added. T he set extended-prom pt command enables support for a defined set of escape sequences that can be used to display various information. T he show extended-prom pt command can be used to determine whether the extended prompt is enabled. New set basenam es-m ay-differ and show basenam es-m ay-differ commands have been added. T he set basenam es-m ay-differ command enables support for source files with multiple base names. T he show basenam es-m ay-differ command can be used to determine whether this support is enabled. T he default option is off to allow faster GDB operations. A new command line option -ix (or --init-com m and) has been added. T his option acts like -x (or --com m and), but is executed before loading the debugged program. A new command line option -iex (or --init-eval-com m and) has been added. T his option acts like -ex (or --eval-com m and), but is executed before loading the debugged program. T he info os command has been changed and can now display information on several objects managed by the operating system, in particular: T he info os procgroups command lists process groups. T he info os files command lists file descriptors. T he info os sockets command lists internet-domain sockets. T he info os shm command lists shared-memory regions. T he info os sem aphores command lists semaphores. T he info os m sg command lists message queues. T he info os m odules command lists loaded kernel modules. GDB now has support for Static Defined Tracing (SDT ) probes. Currently, the only implemented back end is for SystemT ap probes (the sys/sdt.h header file). You can set a breakpoint by using the new -probe, -pstap, or -probe-stap options, and inspect the probe arguments by using the new $_probe_arg family of convenience variables. T he sym bol-reloading option has been deleted. gdbserver now supports ST DIO connections, for example: 153 Red Hat D eveloper Toolset 2.x User Guide (gdb) target remote | ssh myhost gdbserver - hello GDB is now able to print flag enums. In a flag enum, all enumerator values have no bits in common when pairwise AND-ed. When GDB prints a value whose type is a flag enum, GDB shows all the constants; for example, for enum E { ONE = 1, T WO = 2}: (gdb) print (enum E) 3 $1 = (ONE | TWO) T he file name part of a linespec now matches trailing components of a source file name. For example, break gcc/expr.c:1000 now sets a breakpoint in the build/gcc/expr.c file, but not in build/libcpp/expr.c. T he info proc and generate-core-file commands now work on remote targets connected to gdbserver. T he command info catch has been removed. T he Ada-specific catch exception and catch assert commands now accept conditions at the end of the command. T he info static-tracepoint-m arker command now works on native targets with an inprocess agent. GDB can now set breakpoints on inline functions. T he .gdb_index section has been updated to include symbols for inline functions. By default, GDB now ignores older .gdb_index sections until their .gdb_index sections can be recreated. T he new command set use-deprecated-index-sections on causes GDB to use any older .gdb_index sections it finds. If this option is set, the ability to set breakpoints on inline functions is lost in symbol files with older .gdb_index sections. T he .gdb_index section has also been updated to record more information about each symbol. GDB now provides Ada support for GDB/MI Variable Objects. GDB now supports breakpoint always-inserted m ode in the record target. gdbserver now supports evaluation of breakpoint conditions. Note that you can instruct GDB to send the breakpoint conditions in bytecode form, but gdbserver only reports the breakpoint trigger to GDB when its condition evaluates to true. T he z0/z1 breakpoint insertion packets have been extended to carry a list of conditional expressions over to the remote stub depending on the condition evaluation mode. You can use the set rem ote conditional-breakpoints-packet command to control the use of this extension. A new RSP packet QProgram Signals can be used to specify the signals the remote stub can pass to the debugged program without GDB involvement. A new command -info-os has been added as the MI equivalent of info os. Output logs, such as set logging and related, now include MI output. New set use-deprecated-index-sections on|off and show use-deprecated-indexsections on|off commands have been added. T hese commands allow you to control the use of deprecated .gdb_index sections. New catch load and catch unload commands have been added. T hese commands allow you to stop execution of a debugged program when a shared library is loaded or unloaded. A new command enable count has been added. T his command allows you to auto-disable a breakpoint after several hits. A new command info vtbl has been added. T his command allows you to show the virtual method tables for C++ and Java objects. 154 Changes in Version 2.0 A new command explore has been added. It supports two subcommands explore value and explore type, and allows you to recursively explore values and types of expressions. Note that this command is only available with Python-enabled GDB. A new command dprintf location,format,args... has been added. T his command allows you to create a dynamic printf-type breakpoint, which performs a printf-like operation and then resumes program execution. New set print sym bol and show print sym bol commands have been added. T hese commands allow you to control whether GDB attempts to display the symbol, if any, that corresponds to addresses it prints. T his functionality is enabled by default, but you can restore the previous behavior by running the set print sym bol off command. New set breakpoint condition-evaluation and show breakpoint conditionevaluation commands have been added. T hese commands allow you to control whether breakpoint conditions are evaluated by GDB (the host option), or by gdbserver (the target option). T he default option, auto, chooses the most efficient available mode. New set dprintf-style gdb|call|agent and show dprintf-style commands have been added. T hese commands allow you to control the way in which a dynamic printf is performed: the gdb option requests a GDB printf command, call causes dprintf to call a function in the inferior, and agent requests that the target agent such as gdbserver does the printing. New set dprintf-function expression, show dprintf-function, set dprintfchannel expression, and show dprintf-channel commands have been added. T hese commands allow you to set the function and optional first argument to the call when using the call style of dynamic printf. New set disconnected-dprintf on|off and show disconnected-dprintf commands have been added. T hese commands allow you to control whether agent-style dynamic printfs continue to be in effect after GDB disconnects. T he following changes have been made to the C++ language support since the release of the GNU Debugger included in Red Hat Enterprise Linux 6.2: When debugging a template instantiation, parameters of the template are now put in scope. T he following changes have been made to the Python scripting support since the release of the GNU Debugger included in Red Hat Enterprise Linux 6.2: T he register_pretty_printer function in module gdb.printing now takes an optional replace argument. T he m aint set python print-stack on|off command has been deprecated and will be deleted in GDB 7.5. T he new command set python print-stack none|full|m essage has replaced it. A prompt substitution hook (prom pt_hook) is now available to the Python API. A new Python module gdb.prom pt has been added to the GDB Python modules library. Python commands and convenience-functions located in data_directory/python/gdb/com m and/ and data_directory/python/gdb/function/ are now automatically loaded on GDB start-up. Blocks now provide four new attributes: global_block, static_block, is_static, and is_global. T he gdb.breakpoint function has been deprecated in favor of gdb.breakpoints. A new class gdb.FinishBreakpoint is provided. T ype objects for struct and union types now allow access to the fields using standard Python 155 Red Hat D eveloper Toolset 2.x User Guide dictionary (mapping) methods. A new event gdb.new_objfile has been added. A new function deep_item s has been added to the gdb.types module. T he function gdb.Write now accepts an optional keyword stream . Parameters can now be sub-classed in Python, which allows for implementation of the get_set_doc and get_show_doc functions. Symbols, Symbol T able, Symbol T able and Line, Object Files, Inferior, Inferior T hread, Blocks, and Block Iterator APIs now have an is_valid method. Breakpoints can now be sub-classed in Python, which allows for implementation of the stop function that is executed each time the inferior reaches that breakpoint. A new function gdb.lookup_global_sym bol has been added. T his function can be used to look up a global symbol. GDB values in Python are now callable if the value represents a function. A new module gdb.types has been added. A new module gdb.printing has been added. New commands info pretty-printers, enable pretty-printer, and disable prettyprinter have been added. A new gdb.param eter("directories") function call is now available. A new function gdb.newest_fram e has been added. T his function can be used to return the newest frame in the selected thread. T he gdb.InferiorT hread class now supports a new nam e attribute. Support for inferior events has been added. Python scripts can now add observers in order to be notified of events occurring in the process being debugged. GDB commands implemented in Python can now be put in the gdb.COMMAND_USER command class. T he m aint set python print-stack on|off command has been removed and replaced by set python print-stack. A new class gdb.printing.FlagEnum erationPrinter has been added. T his class can be used to apply flag enum -style pretty-printing to enums. T he gdb.lookup_sym bol function now works correctly when there is no current frame. T he gdb.Sym bol object now has an additional attribute line. T his attribute holds the line number in the source at which the symbol was defined. T he gdb.Sym bol object now has an additional attribute needs_fram e, and a new method value. T he needs_fram e attribute indicates whether the symbol requires a frame to compute its value, and the value method computes the symbol's value. T he gdb.Value object now has a new method referenced_value. T his method can be used to dereference a pointer as well as C++ reference values. T he gdb.Sym tab object now has two new methods, global_block and static_block. T hese methods return the global and static blocks (as gdb.Block objects) of the underlying symbol table respectively. A new method gdb.find_pc_line returns the gdb.Sym tab_and_line object associated with a PC value. T he gdb.Sym tab_and_line object now has an additional attribute last. T his attribute holds the end of the address range occupied by the code for the current source line. Compatibility Changes 156 Changes in Version 2.0 A new command info auto-load has been added and can be used to display the status of various automatically loaded files. T he info auto-load gdb-scripts command lists automatically loaded canned sequences of commands, info auto-load python-scripts displays the status of automatically loaded Python scripts, info auto-load local-gdbinit displays whether a local .gdbinit file in the current working directory is loaded, and info autoload libthread-db displays whether the inferior-specific thread debugging shared library is loaded. New commands set auto-load and show auto-load have been added and can be used to control automatic loading of files: T he set auto-load gdb-scripts and show auto-load gdb-scripts commands control automatic loading of GDB scripts. T he set auto-load python-scripts and show auto-load python-scripts commands control automatic loading of Python scripts. T he set auto-load local-gdbinit and show auto-load local-gdbinit commands control automatic loading of .gdbinit from the current working directory. T he set auto-load libthread-db and show auto-load libthread-db commands control automatic loading of inferior-specific libthread_db. T he set auto-load scripts-directory and show auto-load scripts-directory commands control the list of directories from which to automatically load GDB and Python scripts. T he set auto-load safe-path and show auto-load safe-path commands control the list of directories from which it is safe to automatically load all previously mentioned items. T he set debug auto-load and show debug auto-load commands control displaying of debugging information for all previously mentioned items. T he set auto-load off command can be used to disable automatic loading globally. You can also use show auto-load with no subcommand to display current settings of all previously mentioned items. T he m aint set python auto-load on|off command has been replaced with set autoload python-scripts on|off. T he m aintenance print section-scripts command has been renamed to info autoload python-scripts [pattern] and is no longer classified as a maintenance-only command. Support for the Guile extension language has been removed. T he GNU Debugger has been adapted to follow GCC's rules on accessing volatile objects when reading or writing target state during expression evaluation. B.6.3. Changes Since Red Hat Enterprise Linux 5.9 In addition to the above changes, the features below have been added since the release of GDB included in Red Hat Enterprise Linux 5.9. New Features For remote targets, debugging of shared libraries is now supported by default. New commands set observer and show observer have been added. T he set observer command accepts on or off as an argument and can be used to allow or disallow the GNU Debugger to affect the execution of the debugged program. Use the show observer command to determine whether observer mode is enabled. A new convenience variable $_thread has been added. T his variable stores the number of the current thread. T he source command now accepts -s as a valid option. T his option can be used to search for the 157 Red Hat D eveloper Toolset 2.x User Guide script in the source search path regardless of the path in the file name. Support for tracepoints, including fast and static tracepoints, has been added to gdbserver. T he --batch command line option has been adapted to disable pagination and queries. Direct support for the reading and writing byte, word, and double-word x86 general purpose registers such as $al has been added. T he com m ands command now accepts a range of breakpoints as an argument. T he rbreak command now accepts a file name as part of its argument. T his can be used to limit the functions selected by the supplied regular expression to those that are defined in the specified file. Support for multi-program (sometimes referred to as multi-executable or multi-exec) debugging has been added. In particular, the GNU Debugger now supports the following commands: T he add-inferior command can be used to add a new inferior. T he clone-inferior command can be used to create a copy of an inferior with the same executable loaded. T he rem ove-inferior command accepts an inferior ID as an argument and can be used to remove an inferior. Support for trace state variables has been added. In particular, the GNU Debugger now supports the following commands: T he tvariable $variable_name [= expression] command can be used to define or modify a trace state variable. T he info tvariables command can be used to display a list of currently defined trace state variables and their values. T he delete tvariable $variable_name... command can be used to delete one or more trace state variables. A new ftrace has been added. T his command accepts a function name, a line number, or an address as an argument, and can be used to define a fast tracepoint at that location. Support for disconnected tracing, trace files, and circular trace buffer has been added. A new teval command has been added. T his command accepts one or more expressions to evaluate at a tracepoint. T he GNU Debugger has been adapted to parse the 0b prefix of binary numbers exactly the same way as the GNU Compiler Collection. T he GNU Debugger now supports the following commands for process record and replay: New commands set record m em ory and show record m em ory have been added. T he set record m em ory command accepts on or off as an argument and can be used to enable or disable stopping the inferior when a memory change of the next instruction cannot be recorded. Use the show record m em ory-query command to determine whether this feature is enabled. A new command record save has been added. T his command accepts a file name as an argument and can be used to save the execution log to a file. A new command record restore has been added. T his command accepts a file name as an argument and can be used to restore the execution log from a file. A new command eval has been added. T his command accepts a format string followed by one or more arguments, transforms it to a command, and then executes it. A new command save breakpoints has been added. T his command accepts a file name as an argument and can be used to store all currently defined breakpoints to a file. T o restore the saved breakpoints from this file, use the source command. New commands set m ay-write-registers, set m ay-write-m em ory, set m ay-insertbreakpoints, set m ay-insert-tracepoints, set m ay-insert-fast-tracepoints, and 158 Changes in Version 2.0 set m ay-interrupt have been added. All of these commands accept either on or off as an argument, and can be used to set individual permissions for the target. A new command m ain info program -spaces has been added. T his command can be used to display information about currently loaded program spaces. New commands set rem ote interrupt-sequence and show rem ote interruptsequence have been added. T he set rem ote interrupt-sequence command accepts CtrlC, BREAK, and BREAK-g as valid arguments, and can be used to specify which interrupt sequence to send to the remote target in order to interrupt its execution. Use the show rem ote interruptsequence to determine the current setting. New commands set rem ote interrupt-on-connect and show rem ote interrupt-onconnect have been added. T he set rem ote interrupt-on-connect accepts either on or off as an argument, and can be used to enable sending an interrupt sequence to the remote target when the GNU Debugger connects to it. Use the show rem ote interrupt-on-connect command to determine whether this feature is enabled. T he set rem otebreak and show rem otebreak commands have been deprecated and users are advised to use set rem ote interrupt-sequence and show rem ote interruptsequence instead. T he disassem ble command has been adapted to accept two arguments in the form of start,+length. T he source command can now be used to read commands from Python scripts. T he following changes have been made to the C++ language support since the release of the GNU Debugger included in Red Hat Enterprise Linux 5.8: Argument-dependent lookup (ADL) now directs function search to the namespaces of its arguments regardless of whether the namespace has been imported. In addition to member operators, the GNU Debugger can now look up operators that are: defined in the global scope, defined in a namespace and imported via the using directive, implicitly imported from an anonymous namespace, or the argument-dependent lookup (ADL operators. Support for printing of static const class members that are initialized in the class definition has been enhanced. Support for importing of namespaces has been added. T he C++ expression parser has been adapted to handle the cast operators static_cast<>, dynam ic_cast<>, const_cast<>, and reinterpret_cast<>. T he following changes have been made to the Python scripting support since the release of the GNU Debugger in Red Hat Enterprise Linux 5.8: T he GNU Debugger is now installed with a new directory located at /opt/rh/devtoolset2/root/usr/share/gdb/python/. T his directory serves as a standard location for Python scripts written for GDB. T he Python API has been adapted to provide access to symbols, symbol tables, program spaces, breakpoints, inferiors, threads, and frame's code blocks. Users are now also allowed to create custom GDB parameters from the API and manipulate them by using the set and show commands. New functions gdb.target_charset, gdb.target_wide_charset, gdb.progspaces, gdb.current_progspace, and gdb.string_to_argv have been added. A new exception gdb.GdbError has been added. 159 Red Hat D eveloper Toolset 2.x User Guide T he GNU Debugger now searches pretty-printers in the current program space. T he GNU Debugger can now enable or disable pretty-printers individually. T he GNU Debugger has been adapted to look for names of Python scripts to automatically load in a special section named .debug_gdb_scripts. B.7. Changes in strace Red Hat Developer T oolset 2.0 is distributed with strace 4 .7, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version. Below is a comprehensive list of new features in this release. B.7.1. Changes Since Red Hat Enterprise Linux 6.4 and 5.9 T he following features have been added since the release of strace in Red Hat Enterprise Linux 6.4 and 5.9: A new command line option, -y, has been added. T his option can be used to print file descriptor paths. A new command line option, -P, has been added. T his option can be used to filter system calls based on the file descriptor paths. A new command line option, -I, has been added. T his option can be used to control how interactive strace is. A new command line utility, strace-log-m erge, has been added. T his utility can be used to merge timestamped strace output into a single file. T he strace utility now uses optimized interfaces to extract data from the traced process for better performance. T he strace utility now provides improved support for decoding of arguments for various system calls. In addition, a number of new system calls are supported. B.8. Changes in SystemTap Red Hat Developer T oolset 2.0 is distributed with SystemT ap 2.1, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of new features in this release. B.8.1. Changes Since Red Hat Developer Toolset 1.1 T he following features have been added since the release of SystemT ap included in Red Hat Developer T oolset 1.1: SystemT ap has been updated to provide experimental support for Dyninst-based probing in the user space. Users can now execute the stap utility with the --dyninst command line option to instrument their own programs without the need to acquire root privileges. SystemT ap is now distributed with a number of manual pages that provide a detailed explanation of common errors: T he error::buildid(7stap) manual page documents build-id verification failures. T he error::dwarf(7stap) manual page documents common DWARF debuginfo quality problems. T he error::fault(7stap) manual page documents memory access faults. T he error::inode-uprobes(7stap) manual page documents current limitations of inodeuprobes. 160 Changes in Version 2.0 T he error::pass1(7stap) manual page documents pass 1 (parsing) errors. T he error::pass2(7stap) manual page documents pass 2 (elaboration) errors. T he error::pass3(7stap) manual page documents pass 3 (translation) errors. T he error::pass4 (7stap) manual page documents pass 4 (compilation) errors. T he error::pass5(7stap) manual page documents pass 5 (execution) errors. T he error::process-tracking(7stap) manual page documents user-space process tracking errors. T he error::reporting(7stap) manual page documents how to report SystemT ap bugs. T he scripting language used by SystemT ap now supports the =~ operator. Users can use this operator to match regular expressions. T he preprocessor used by the stap utility now supports an experimental macro facility. Users can use the following construct to define new macros: @define name(parameter...) %( body %) Refer to the PREPROCESSOR MACROS section of the stap(1) manual page for more information on how to use this feature. T he backtrace-related tapset functions have been improved and standardized. B.9. Changes in OProfile Red Hat Developer T oolset 2.0 is distributed with OProfile 0.9.8, which provides a number of bug fixes and feature enhancements over the Red Hat Enterprise Linux system version and the version included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of new features in this release. B.9.1. Changes Since Red Hat Developer Toolset 1.1 T he following features have been added since the release of OProfile included in Red Hat Developer T oolset 1.1: A new command line utility, operf, has been added. T his utility can be executed by a non-root user and can be used to collect profiling data. Important T he operf utility relies on a kernel feature that is currently not available in Red Hat Enterprise Linux 5. Consequently, this utility only works and is supported on Red Hat Enterprise Linux 6. OProfile now supports Intel processors code-named Ivy Bridge. B.9.2. Changes Since Red Hat Enterprise Linux 5.9 T he following features have been added since the release of OProfile included in Red Hat Enterprise Linux 5.9: OProfile now supports AMD family11h, family12h, family14h, and AMD family15h processors. Generation of XML output has been corrected. Handling of the --session-dir command line option has been improved and a possible buffer overflow in the XML generator has been fixed. 161 Red Hat D eveloper Toolset 2.x User Guide B.10. Changes in Valgrind Red Hat Developer T oolset 2.0 is distributed with Valgrind 3.8.1, which provides a number of bug fixes over the version included in Red Hat Developer T oolset 1.1. Below is a comprehensive list of changes in this release. B.10.1. Changes Since Red Hat Developer Toolset 1.1 T he following features have been added since the release of Valgrind included in Red Hat Developer T oolset 1.1: T he DWARF debug information for Valgrind is now distributed in a separate package, devtoolset-2valgrind-debuginfo. T he SGCHECK OPTIONS section of the valgrind(1) manual page has been corrected and no longer includes the BBV options. As well, the BBV options are now listed in a separate section. B.10.2. Changes Since Red Hat Enterprise Linux 5.9 In addition to the above changes, the following features have been added since the release of Valgrind 3.5.0 included in Red Hat Enterprise Linux 5.9: When running in 64-bit mode, Valgrind now supports the SSE4.2 instruction set with the exception of SSE4.2 AES instructions. In 32-bit mode, Valgrind only provides support up to and including the SSSE3 instruction set. A new processing script cg_diff has been added to Cachegrind. T his processing script can find the difference between two profiles, and can therefore be used to evaluate the performance effects of a change in a program. T he behavior of the cg_annotate's rarely-used --threshold option has been changed. Callgrind now supports branch prediction simulation and can optionally count the number of executed global bus events. Note that in order to use this functionality for a better approximation of a “Cycle Estimation” as a derived event, you must manually update the event formula in KCachegrind. T o accommodate machines with three levels of caches, both Cachegrind and Callgrind now refer to the LL (last-level) cache rather than the L2 cache. When Cachegrind or Callgrind auto-detects the cache configuration of such a machine, it now runs the simulation as if the L2 cache is not present. Consequently, the results are less likely to match the true result for the machine and should not be considered authoritative, but provide a general idea about a program's locality. A new command line option --pages-as-heap has been added to Massif. When this option is enabled, Massif tracks memory allocations at the level of memory pages (as mapped by m m ap, brk and similar functions) instead of tracking allocations at the level of heap blocks (as allocated with m alloc, new, or new[]). Each mapped page is treated as its own block. Interpreting the page-level output is harder than the heap-level output, but allows you to account for every byte of memory used by a program. By default, the --pages-as-heap option is disabled. New command line options --free-is-write and --trace-alloc have been added to DRD. T he --free-is-write option allows you to detect reading from already freed memory, the -trace-alloc can be used to trace of all memory allocations and deallocations. A number of new allocations have been added to DRD. As well, you can now annotate custom barrier implementations and benign races on static variables. DRD's happens before and happens after annotations have been enhanced and can be used to annotate, for example, a smart pointer implementation. Helgrind's annotation set has been significantly improved to provide a general set of annotations to describe locks, semaphores, barriers, and condition variables. In addition, Helgrind now supports 162 Changes in Version 2.0 annotations to describe thread-safe reference counted heap objects. A new command line option --show-possibly-lost has been added to Memcheck. By default this option is enabled and causes the leak detector to show possibly-lost blocks. A new experimental heap profiler, DHAT (Dynamic Heap Analysis T ool), has been added. DHAT keeps track of allocated heap blocks, and also inspects every memory reference to see which block (if any) is being accessed. T his gives a lot of insight into block lifetimes, utilization, turnover, liveness, and the location of hot and cold fields. You can use DHAT to do hot-field profiling. Support for unfriendly self-modifying code has been improved, and the extra overhead incurred by -sm c-check=all has been reduced by approximately a factor of 5 as compared with the previous version of Valgrind. A new command line option --fullpath-after has been added. T his option can be used to display directory names for source files in error messages, and is combined with a flexible mechanism for specifying which parts of the paths should be shown. A new command line option --require-text-sym bol has been added. T his option stops the execution if a specified symbol is not found in a given shared object when loaded into the process. As a result, working with function intercepting and wrapping is now safer and more reliable. Valgrind now implements more reliable stack unwinding on amd64-linux, particularly in the presence of function wrappers, and with gcc-4.5 compiled code. Valgrind now implements modest scalability (performance improvements) for very large, long-running applications. Valgrind now provides improved support for analyzing programs that are running in Wine. Users can now include the valgrind/valgrind.h, valgrind/m em check.h, and valgrind/drd.h header files in Windows programs that are compiled with MinGW or one of the Microsoft Visual Studio compilers. 163 Red Hat D eveloper Toolset 2.x User Guide Revision History Revision 2.0-2 T ue 11 Mar 2014 Red Hat Developer T oolset 2.1 GA release of the User Guide. Jaromír Hradílek Revision 1.0-3 T ue 11 Feb 2014 Red Hat Developer T oolset 2.1 Beta release of the User Guide Jaromír Hradílek Revision 1.0-2 T ue 10 Sep 2013 Red Hat Developer T oolset 2.0 GA release of the User Guide. Jaromír Hradílek Revision 1.0-1 T ue 06 Aug 2013 Jaromír Hradílek Red Hat Developer T oolset 2.0 Beta-2 release of the User Guide. Revision 1.0-0 T ue 28 May 2013 Jaromír Hradílek Red Hat Developer T oolset 2.0 Beta-1 release of the User Guide. Index A ABI - compatibility, ABI Compatibility addr2line - features, New Features - overview, binutils - usage, Using Other Binary T ools application binary interface (see ABI) ar - overview, binutils - usage, Using Other Binary T ools as (see GNU assembler) assembling (see GNU assembler) B bfd - features, New Features binutils - 164 documentation, Additional Resources features, Main Features installation, Installing binutils overview, binutils Revision History - usage, Using the GNU Assembler, Using the GNU Linker, Using Other Binary T ools - version, About Red Hat Developer T oolset, binutils C C programming language - compiling, Using the C Compiler, Preparing a Program for Debugging - running, Running a C Program - support, GNU C Compiler C++ programming language - compiling, Using the C++ Compiler, Preparing a Program for Debugging - running, Running a C++ Program - support, GNU C++ Compiler C++11 (see GNU Compiler Collection) c++filt - overview, binutils - usage, Using Other Binary T ools C11 (see GNU Compiler Collection) Cachegrind - overview, Valgrind - usage, Using Valgrind Callgrind - overview, Valgrind - usage, Using Valgrind compatibility - GNU Compiler Collection, Language Compatibility, Compatibility Changes, Fortran 2003 Compatibility, Fortran 2008 Compatibility, Fortran 77 Compatibility, ABI Compatibility, Debugging Compatibility, Other Compatibility - Red Hat Developer T oolset, Compatibility compiling (see GNU Compiler Collection) D debugging (see GNU Debugger) Developer T oolset (see Red Hat Developer T oolset) documentation - Red Hat Product Documentation, Accessing Red Hat Product Documentation DRD 165 Red Hat D eveloper Toolset 2.x User Guide - overview, Valgrind - usage, Using Valgrind dwp - overview, binutils - usage, Using Other Binary T ools dwz - documentation, Additional Resources installation, Installing dwz overview, dwz usage, Using dwz version, About Red Hat Developer T oolset, dwz - documentation, Additional Resources installation, Installing Dyninst overview, Dyninst usage, Using Dyninst version, About Red Hat Developer T oolset, Dyninst - configuration, Using the Red Hat Enterprise Linux T oolchain documentation, Additional Resources installation, Installing Eclipse overview, Eclipse usage, Using Eclipse version, About Red Hat Developer T oolset, Eclipse Dyninst E Eclipse elfedit - features, New Features - overview, binutils - usage, Using Other Binary T ools elfutils - documentation, Additional Resources installation, Installing elfutils overview, elfutils usage, Using elfutils version, About Red Hat Developer T oolset, elfutils eu-addr2line - features, Changes Since Red Hat Enterprise Linux 5.9 - overview, elfutils - usage, Using elfutils 166 Revision History eu-ar - features, Changes Since Red Hat Enterprise Linux 6.4 - overview, elfutils - usage, Using elfutils eu-elfcmp - features, Changes Since Red Hat Enterprise Linux 5.9 - overview, elfutils - usage, Using elfutils eu-elflint - features, Changes Since Red Hat Enterprise Linux 6.4 - overview, elfutils - usage, Using elfutils eu-findtextrel - overview, elfutils - usage, Using elfutils eu-make-debug-archive - overview, elfutils - usage, Using elfutils eu-nm - features, Changes Since Red Hat Enterprise Linux 6.4 - overview, elfutils - usage, Using elfutils eu-objdump - overview, elfutils - usage, Using elfutils eu-ranlib - overview, elfutils - usage, Using elfutils eu-readelf - features, Changes Since Red Hat Enterprise Linux 6.4, Changes Since Red Hat Enterprise Linux 5.9 - overview, elfutils - usage, Using elfutils eu-size 167 Red Hat D eveloper Toolset 2.x User Guide - overview, elfutils - usage, Using elfutils eu-strings - overview, elfutils - usage, Using elfutils eu-strip - features, Changes Since Red Hat Enterprise Linux 6.4, Changes Since Red Hat Enterprise Linux 5.9 - overview, elfutils - usage, Using elfutils eu-unstrip - overview, elfutils - usage, Using elfutils F feedback - contact information for this manual, We Need Feedback! Fortran programming language - compiling, Using the Fortran Compiler - running, Running a Fortran Program - support, GNU Fortran Compiler G g++ (see GNU Compiler Collection) GAS (see GNU assembler) GCC (see GNU Compiler Collection) gcc (see GNU Compiler Collection) GDB (see GNU Debugger) gfortran (see GNU Compiler Collection) Git - configuration, Configuring Git documentation, Additional Resources installation, Installing Git overview, Git usage, Using Git version, About Red Hat Developer T oolset, Git Global Support Services 168 Revision History - contacting, Contacting Global Support Services GNU assembler - documentation, Additional Resources - installation, Installing binutils - overview, binutils - usage, Using the GNU Assembler GNU Binutils (see binutils) GNU Compiler Collection - C support, GNU C Compiler - C++ support, GNU C++ Compiler - compatibility, Language Compatibility, Compatibility Changes, Fortran 2003 Compatibility, Fortran 2008 Compatibility, Fortran 77 Compatibility, ABI Compatibility, Debugging Compatibility, Other Compatibility - documentation, Additional Resources - features, Main Features, Status and Features, New Features, Fortran 2003 Features, Fortran 2008 Features - Fortran support, GNU Fortran Compiler - installation, Installing the C Compiler, Installing the C++ Compiler, Installing the Fortran Compiler - overview, GNU Compiler Collection (GCC) - usage, Using the C Compiler, Using the C++ Compiler, Using the Fortran Compiler, Preparing a Program for Debugging - version, About Red Hat Developer T oolset, GNU Compiler Collection (GCC) GNU Debugger - documentation, Additional Resources - features, Main Features - installation, Installing the GNU Debugger - overview, GNU Debugger (GDB) - preparation, Preparing a Program for Debugging - usage, Running the GNU Debugger, Listing Source Code, Setting Breakpoints, Starting Execution, Displaying Current Values, Continuing Execution - version, About Red Hat Developer T oolset, GNU Debugger (GDB) GNU linker - documentation, Additional Resources - installation, Installing binutils - overview, binutils - usage, Using the GNU Linker gprof - features, New Features - overview, binutils - usage, Using Other Binary T ools 169 Red Hat D eveloper Toolset 2.x User Guide GSS (see Global Support Services) H Helgrind - overview, Valgrind - usage, Using Valgrind help - getting help, Do You Need Help? - Global Support Services, Contacting Global Support Services - Red Hat Product Documentation, Accessing Red Hat Product Documentation L ld (see GNU linker) linking (see GNU linker) M Massif - overview, Valgrind - usage, Using Valgrind Memcheck - overview, Valgrind - usage, Using Valgrind memstomp - documentation, Additional Resources - installation, Installing memstomp - overview, memstomp - usage, Using memstomp - version, About Red Hat Developer T oolset N nm - overview, binutils - usage, Using Other Binary T ools O objcopy - features, New Features - overview, binutils - usage, Using Other Binary T ools 170 Revision History objdump - features, New Features - overview, binutils - usage, Using Other Binary T ools opannotate - overview, OProfile - usage, Using OProfile oparchive - overview, OProfile - usage, Using OProfile opcontrol - overview, OProfile - usage, Using OProfile opgprof - overview, OProfile - usage, Using OProfile ophelp - overview, OProfile - usage, Using OProfile opimport - overview, OProfile - usage, Using OProfile opjitconv - overview, OProfile - usage, Using OProfile opreport - overview, OProfile - usage, Using OProfile OProfile - documentation, Additional Resources installation, Installing OProfile overview, OProfile usage, Using OProfile version, About Red Hat Developer T oolset, OProfile 171 Red Hat D eveloper Toolset 2.x User Guide oprofiled - overview, OProfile - usage, Using OProfile R ranlib - overview, binutils - usage, Using Other Binary T ools readelf - features, New Features - overview, binutils - usage, Using Other Binary T ools Red Hat Developer T oolset - compatibility, Compatibility - documentation, Additional Resources, Accessing Red Hat Product Documentation - features, Main Features - installation, Installing Red Hat Developer T oolset - overview, About Red Hat Developer T oolset - subscription, Getting Access to Red Hat Developer T oolset - support, About Red Hat Developer T oolset - uninstallation, Uninstalling Red Hat Developer T oolset - update, Updating Red Hat Developer T oolset Red Hat Enterprise Linux - documentation, Additional Resources, Accessing Red Hat Product Documentation - supported versions, Compatibility Red Hat Subscription Management - subscription, Using Red Hat Subscription Management RHN Classic - subscription, Using RHN Classic S scl (see Software Collections) size - overview, binutils - usage, Using Other Binary T ools Software Collections - documentation, Additional Resources, Accessing Red Hat Product Documentation 172 Revision History - overview, About Red Hat Developer T oolset stap - overview, SystemT ap - usage, Using SystemT ap, Using Dyninst with SystemT ap stap-merge - overview, SystemT ap - usage, Using SystemT ap stap-prep - overview, SystemT ap - usage, Installing SystemT ap stap-report - overview, SystemT ap - usage, Using SystemT ap staprun - overview, SystemT ap - usage, Using SystemT ap stapsh - overview, SystemT ap - usage, Using SystemT ap strace - documentation, Additional Resources installation, Installing strace overview, strace usage, Using strace version, About Red Hat Developer T oolset, strace strings - overview, binutils - usage, Using Other Binary T ools strip - overview, binutils - usage, Using Other Binary T ools support - Red Hat Developer T oolset, About Red Hat Developer T oolset 173 Red Hat D eveloper Toolset 2.x User Guide SystemT ap - documentation, Additional Resources - installation, Installing SystemT ap - overview, SystemT ap - usage, Using SystemT ap, Using Dyninst with SystemT ap - version, About Red Hat Developer T oolset, SystemT ap V Valgrind - documentation, Additional Resources installation, Installing Valgrind overview, Valgrind usage, Using Valgrind version, About Red Hat Developer T oolset, Valgrind version - version, memstomp 174
